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All questions of Diffusion for Chemical Engineering Exam
What is the molecular weight of ammonia?- a)31
- b)53
- c)29
- d)39
Correct answer is option 'C'. Can you explain this answer?
What is the molecular weight of ammonia?
a)
31
b)
53
c)
29
d)
39
|
Parth Banerjee answered |
Formula of Sulphur-dioxide is SO 2.
Fick’s law is given by the formula - a)N b = – D b c d C b/d x
- b)N b = – 2 D b c d C b/d x
- c)N b = – 3 D b c d C b/d x
- d)N b = – 4 D b c d C b/d x
Correct answer is option 'A'. Can you explain this answer?
Fick’s law is given by the formula
a)
N b = – D b c d C b/d x
b)
N b = – 2 D b c d C b/d x
c)
N b = – 3 D b c d C b/d x
d)
N b = – 4 D b c d C b/d x
|
Sagarika Patel answered |
Fick's laws of diffusion describe diffusion and were derived by Adolf Fick in 1855. They can be used to solve for the diffusion coefficient, D. Fick's first law can be used to derive his second law which in turn is identical to the diffusion equation.
Diffusion co-efficient in molecular diffusion is estimated by _________- a)Daltons law
- b)Diffusion law
- c)Ficks law
- d)None of the mentioned
Correct answer is option 'C'. Can you explain this answer?
Diffusion co-efficient in molecular diffusion is estimated by _________
a)
Daltons law
b)
Diffusion law
c)
Ficks law
d)
None of the mentioned
|
Milan Sen answered |
Explanation: Ficks law is the ratio of J-flux to the concentration gradient.
Before collision, the distance between the two particles is mean free path.- a)True
- b)False
Correct answer is 'B'. Can you explain this answer?
Before collision, the distance between the two particles is mean free path.
a)
True
b)
False
|
Anjana Sharma answered |
Mean free path is the average distance an object will move between collisions. The actual distance a particle, such as a molecule in a gas, will move before a collision, called free path, cannot generally be given because its calculation would require knowledge of the path of every particle in the region.
The Judges of the High Court hold office
- a)during the pleasure of the Chief Justice of India
- b)as long as they desire till
- c)till they have attained 65 years of age
- d)they have attained 62 years of age
Correct answer is option 'D'. Can you explain this answer?
The Judges of the High Court hold office
a)
during the pleasure of the Chief Justice of India
b)
as long as they desire till
c)
till they have attained 65 years of age
d)
they have attained 62 years of age
|
Aman Kapoor answered |
The correct answer is option D: the Judges of the High Court hold office till they have attained 62 years of age. Let's discuss this answer in detail.
Explanation:
1. Tenure of Judges:
The tenure of Judges in the High Court is determined by their age. According to the Indian Constitution, the Judges of the High Court hold office till they have attained a certain age limit.
2. Retirement Age:
The retirement age for Judges of the High Court is set at 62 years. This means that once a Judge reaches the age of 62, they are required to retire from their position.
3. Importance of Retirement Age:
The retirement age for Judges is significant to ensure the smooth functioning of the judiciary. It allows for the regular turnover of Judges and provides opportunities for new appointments, ensuring a fresh perspective and continuous development within the judicial system.
4. Judicial Independence:
Setting a retirement age for Judges also helps to maintain the independence of the judiciary. It prevents any undue influence or pressure on Judges to continue in their position beyond a certain age.
5. Uniformity in Retirement Age:
The retirement age of 62 years is applicable for Judges in all High Courts across India. This uniformity helps in maintaining consistency and fairness in the judicial system.
6. Exceptions:
While the retirement age is generally 62 years, there may be certain exceptions or variations based on specific circumstances or laws. For example, in certain cases, the President of India may grant an extension to a Judge's tenure for a limited period.
In conclusion, the correct answer is option D: the Judges of the High Court hold office till they have attained 62 years of age. This retirement age ensures regular turnover, maintains judicial independence, and provides consistency in the judicial system.
Explanation:
1. Tenure of Judges:
The tenure of Judges in the High Court is determined by their age. According to the Indian Constitution, the Judges of the High Court hold office till they have attained a certain age limit.
2. Retirement Age:
The retirement age for Judges of the High Court is set at 62 years. This means that once a Judge reaches the age of 62, they are required to retire from their position.
3. Importance of Retirement Age:
The retirement age for Judges is significant to ensure the smooth functioning of the judiciary. It allows for the regular turnover of Judges and provides opportunities for new appointments, ensuring a fresh perspective and continuous development within the judicial system.
4. Judicial Independence:
Setting a retirement age for Judges also helps to maintain the independence of the judiciary. It prevents any undue influence or pressure on Judges to continue in their position beyond a certain age.
5. Uniformity in Retirement Age:
The retirement age of 62 years is applicable for Judges in all High Courts across India. This uniformity helps in maintaining consistency and fairness in the judicial system.
6. Exceptions:
While the retirement age is generally 62 years, there may be certain exceptions or variations based on specific circumstances or laws. For example, in certain cases, the President of India may grant an extension to a Judge's tenure for a limited period.
In conclusion, the correct answer is option D: the Judges of the High Court hold office till they have attained 62 years of age. This retirement age ensures regular turnover, maintains judicial independence, and provides consistency in the judicial system.
This type consists of two statements, one called ‘Assertion’ (A) followed by another statement called ‘Reason’ (R) and the candidate has to choose one of the four alternatives given below:Q.A: Ombudsman is an official appointed by Parliament who is in charge of receiving petitions from the public.
R: Ombudsman is people's representative.- a)Both A and R are true, and R is the correct explanation of A
- b)Both A and R are true but R is not a correct explanation of A.
- c)A is true but R is false.
- d)A is false but R is true.
Correct answer is option 'C'. Can you explain this answer?
This type consists of two statements, one called ‘Assertion’ (A) followed by another statement called ‘Reason’ (R) and the candidate has to choose one of the four alternatives given below:
Q.
A: Ombudsman is an official appointed by Parliament who is in charge of receiving petitions from the public.
R: Ombudsman is people's representative.
R: Ombudsman is people's representative.
a)
Both A and R are true, and R is the correct explanation of A
b)
Both A and R are true but R is not a correct explanation of A.
c)
A is true but R is false.
d)
A is false but R is true.
|
Geetika Choudhary answered |
The premise and the other called the conclusion. The premise is a statement that is used as evidence or support for the conclusion, which is the statement that the argument is trying to prove. This type of argument is called a deductive argument because the conclusion logically follows from the premise. The validity of the argument depends on the truthfulness of the premise. If the premise is true, then the conclusion must also be true. However, if the premise is false, then the conclusion is also false. Deductive arguments are often used in mathematics and logic, where the rules of deduction are well-established.
A reaction 3A+2B+C=1.5D+E occurs in a reactor at steady state. What will be the value of the flux ratio NA/ND - a)-2
- b)-0.5
- c)2
- d)-0.15
Correct answer is 'A'. Can you explain this answer?
A reaction 3A+2B+C=1.5D+E occurs in a reactor at steady state. What will be the value of the flux ratio NA/ND
a)
-2
b)
-0.5
c)
2
d)
-0.15
|
Gargi Desai answered |
Explanation: NA/ND= (rate of disappearance of A)/(rate of appearance of D)
= -3/1.5
= -2.
= -3/1.5
= -2.
A solution contains 0.3 moles of solute A, 0.2 moles of B and 0.5 moles of C. What will be the mole fraction of A in the mixture?- a)0.3
- b)0.2
- c)0.5
- d)1
Correct answer is option 'A'. Can you explain this answer?
A solution contains 0.3 moles of solute A, 0.2 moles of B and 0.5 moles of C. What will be the mole fraction of A in the mixture?
a)
0.3
b)
0.2
c)
0.5
d)
1
|
Athira Bajaj answered |
Mole fraction is a way to express the concentration of a particular component in a mixture. It is defined as the ratio of the moles of a component to the total moles of all components in the mixture.
In this case, we are given the number of moles of solute A, B, and C in the solution. To calculate the mole fraction of A, we need to divide the number of moles of A by the total number of moles in the solution.
Let's calculate the total number of moles in the solution first:
Total moles = moles of A + moles of B + moles of C
Total moles = 0.3 + 0.2 + 0.5
Total moles = 1
Now, we can calculate the mole fraction of A:
Mole fraction of A = moles of A / total moles
Mole fraction of A = 0.3 / 1
Mole fraction of A = 0.3
Therefore, the mole fraction of A in the mixture is 0.3.
In this case, we are given the number of moles of solute A, B, and C in the solution. To calculate the mole fraction of A, we need to divide the number of moles of A by the total number of moles in the solution.
Let's calculate the total number of moles in the solution first:
Total moles = moles of A + moles of B + moles of C
Total moles = 0.3 + 0.2 + 0.5
Total moles = 1
Now, we can calculate the mole fraction of A:
Mole fraction of A = moles of A / total moles
Mole fraction of A = 0.3 / 1
Mole fraction of A = 0.3
Therefore, the mole fraction of A in the mixture is 0.3.
A gas mixture containing 21% O2 and 79% N2 flows through a pipe of circular cross-section of diameter 2cm at atmospheric pressure. The velocity of O2 is 0.04m/s and N2 is 0.035m/s.Q. What is the value of Volume average velocity?- a)0.036
- b)0.035
- c)0.034
- d)0.033
Correct answer is option 'A'. Can you explain this answer?
A gas mixture containing 21% O2 and 79% N2 flows through a pipe of circular cross-section of diameter 2cm at atmospheric pressure. The velocity of O2 is 0.04m/s and N2 is 0.035m/s.
Q. What is the value of Volume average velocity?
a)
0.036
b)
0.035
c)
0.034
d)
0.033
|
|
Parth Banerjee answered |
Explanation: Volume average velocity= Molar average velocity.
Prandtl number is given by- a)V/α
- b)2 V/α
- c)3 V/α
- d)4 V/α
Correct answer is option 'A'. Can you explain this answer?
Prandtl number is given by
a)
V/α
b)
2 V/α
c)
3 V/α
d)
4 V/α
|
Shreya Pillai answered |
Explanation: It is related with velocity and temperature profiles.
For the molecular diffusion of liquids, if the diffusing molecules having criteria of steady state diffusion of B over non diffusing A then the N flux of A is- a)1
- b)0
- c)Negative
- d)Infinity
Correct answer is option 'B'. Can you explain this answer?
For the molecular diffusion of liquids, if the diffusing molecules having criteria of steady state diffusion of B over non diffusing A then the N flux of A is
a)
1
b)
0
c)
Negative
d)
Infinity
|
|
Advait Chatterjee answered |
Explanation:
Steady State Diffusion:
- In steady state diffusion, the rate of diffusion of B over non-diffusing A remains constant over time.
- This means that there is a continuous flow of B molecules diffusing through A.
Net Flux of A:
- Since A is not diffusing, the net flux of A would be zero.
- This is because there is no movement of A molecules across the diffusion boundary.
- The net flux is a measure of the amount of substance moving through a unit area in a unit time.
Therefore, in the given scenario where B is diffusing over non-diffusing A in a steady-state diffusion process, the net flux of A would be 0.
Convective mass transfer involves the transportation of material between a boundary surface and a moving fluid or between two immiscible fluids. It is prescribed by the relation - a)2 h m (d C B)
- b)½ h m (d C B)
- c)h m (d C B)
- d)3/2 h m (d C B)
Correct answer is option 'C'. Can you explain this answer?
Convective mass transfer involves the transportation of material between a boundary surface and a moving fluid or between two immiscible fluids. It is prescribed by the relation
a)
2 h m (d C B)
b)
½ h m (d C B)
c)
h m (d C B)
d)
3/2 h m (d C B)
|
|
Uday Mukherjee answered |
Explanation: It is equal to m/A = h m (d C B).
Which one is having minimum melting point?- a)Titanium
- b)Zinc
- c)Uranium
- d)Rhodium
Correct answer is option 'B'. Can you explain this answer?
Which one is having minimum melting point?
a)
Titanium
b)
Zinc
c)
Uranium
d)
Rhodium
|
|
Prasad Sengupta answered |
Explanation: Melting point of zinc is 693 K while that of titanium, uranium and rhodium are 3269 K, 1406 K and 2236 K respectively.
A binary liquid mixture is separated by distillation process. The more volatile A vaporizes while less volatile B gets transported in opposite direction. Latent heat of vaporization of A and B is 0.5unit and 1unit respectively. What will be the relation between molar flux of A and B - a)NA=2NB
- b)2NA=NB
- c)NA=4NB
- d)4NA=NB
Correct answer is option 'A'. Can you explain this answer?
A binary liquid mixture is separated by distillation process. The more volatile A vaporizes while less volatile B gets transported in opposite direction. Latent heat of vaporization of A and B is 0.5unit and 1unit respectively. What will be the relation between molar flux of A and B
a)
NA=2NB
b)
2NA=NB
c)
NA=4NB
d)
4NA=NB
|
Rajat Saini answered |
Explanation: Latent heat of vaporization of A is provided from condensation of B. NA∆HA=NB∆HB.
Find J flux of A ( xA = 0.5) if the total N flux is 6 mol/sq.m sec and N flux of A is 3 mol/sq.m sec.- a)0
- b)1
- c)2
- d)3
Correct answer is option 'A'. Can you explain this answer?
Find J flux of A ( xA = 0.5) if the total N flux is 6 mol/sq.m sec and N flux of A is 3 mol/sq.m sec.
a)
0
b)
1
c)
2
d)
3
|
Sagarika Chopra answered |
Explanation: N flux of A = J flux of A + Total flux N * xA
3= J flux of A + 6 * 0.5
J flux = 0.
3= J flux of A + 6 * 0.5
J flux = 0.
Under which of the following conditions mass average velocity and molar average velocity are equal?- a)In a very dilute solution
- b)If molecular weights of all the species are equal
- c)Always different
- d)In dilute solutions as well as in solutions in which all components have same molecular weights
Correct answer is option 'D'. Can you explain this answer?
Under which of the following conditions mass average velocity and molar average velocity are equal?
a)
In a very dilute solution
b)
If molecular weights of all the species are equal
c)
Always different
d)
In dilute solutions as well as in solutions in which all components have same molecular weights
|
Nandini Mishra answered |
Explanation: None.
Schmidt number is given by the formula- a)2 D/v
- b)v/D
- c)D/v
- d)2 v/D
Correct answer is option 'B'. Can you explain this answer?
Schmidt number is given by the formula
a)
2 D/v
b)
v/D
c)
D/v
d)
2 v/D
|
Mohit Majumdar answered |
Explanation: Schmidt number is defined as the ratio of viscosity and mass diffusivity and is used to characterize fluid flows in which there are simultaneous momentum and mass diffusion convection processes.
Nagar panchayat is otherwise known in Gujarat as- a)Notified Area Committee
- b)Town Area Committee
- c)Cantonment Board
- d)Municipal Corporation
Correct answer is option 'B'. Can you explain this answer?
Nagar panchayat is otherwise known in Gujarat as
a)
Notified Area Committee
b)
Town Area Committee
c)
Cantonment Board
d)
Municipal Corporation
|
|
Ananya Kumari answered |
They problem of among the generity and say dna and type to form here and they among all of say to all they keep
and do to all say learn more and about here and there and possive and exactly and what to all
and decay him say do to form fill him say emerge and do can we do very to all
and they emerge and all the
and do to all say learn more and about here and there and possive and exactly and what to all
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Air at 1 atm and 25 degree Celsius temperature, flows inside a 3 cm diameter tube with a velocity of 5.25 m/s. Determine mass transfer coefficient for iodine transfer from the air stream to the weak surface. Assume the following thermos-physical properties of air
D =0.82 * 10 -6 m2/s
v = 15.5 * 10 -6 m2/s- a)0.0176 m/s
- b)1.0176 m/s
- c)2.0176 m/s
- d)3.0176 m/s
Correct answer is option 'A'. Can you explain this answer?
Air at 1 atm and 25 degree Celsius temperature, flows inside a 3 cm diameter tube with a velocity of 5.25 m/s. Determine mass transfer coefficient for iodine transfer from the air stream to the weak surface. Assume the following thermos-physical properties of air
D =0.82 * 10 -6 m2/s
v = 15.5 * 10 -6 m2/s
D =0.82 * 10 -6 m2/s
v = 15.5 * 10 -6 m2/s
a)
0.0176 m/s
b)
1.0176 m/s
c)
2.0176 m/s
d)
3.0176 m/s
|
|
Shanaya Gupta answered |
Explanation: h m = (Sherwood number) D/d =0.0176 m/s.
The velocity of various components of mixture(21% A, 78% B and 1% C) are:
Velocity is in the form: v⃗=xi+yj+zkVelocity of component A= (0.1, 0, 0)
Velocity of component B= (0, 0.1, 0)
Velocity of component B= (0, 0, 0.1)
Calculate the value of average molar velocity?- a)(0.021, 0.078, 0.01)
- b)(0.1, 0.1, 0.1)
- c)(0, 0 ,0)
- d)(0.079, 0.021, 0.01)
Correct answer is option 'A'. Can you explain this answer?
The velocity of various components of mixture(21% A, 78% B and 1% C) are:
Velocity is in the form: v⃗=xi+yj+zk
Velocity is in the form: v⃗=xi+yj+zk
Velocity of component A= (0.1, 0, 0)
Velocity of component B= (0, 0.1, 0)
Velocity of component B= (0, 0, 0.1)
Calculate the value of average molar velocity?
Velocity of component B= (0, 0.1, 0)
Velocity of component B= (0, 0, 0.1)
Calculate the value of average molar velocity?
a)
(0.021, 0.078, 0.01)
b)
(0.1, 0.1, 0.1)
c)
(0, 0 ,0)
d)
(0.079, 0.021, 0.01)
|
|
Chirag Patel answered |
Calculation of Average Molar Velocity
To calculate the average molar velocity, we need to consider the velocities of each component and their respective mole fractions. Here, we have three components - A, B, and C, with mole fractions of 0.21, 0.78, and 0.01, respectively.
Component A:
The velocity of component A is given as (0.1, 0, 0).
Since its mole fraction is 0.21, we need to multiply the velocity vector by the mole fraction to get the contribution of component A to the average molar velocity.
So, the contribution of component A to the average molar velocity is (0.21 * 0.1, 0.21 * 0, 0.21 * 0) = (0.021, 0, 0).
Component B:
The velocity of component B is given as (0, 0.1, 0).
Similarly, the contribution of component B to the average molar velocity is (0.78 * 0, 0.78 * 0.1, 0.78 * 0) = (0, 0.078, 0).
Component C:
The velocity of component C is given as (0, 0, 0.1).
The contribution of component C to the average molar velocity is (0.01 * 0, 0.01 * 0, 0.01 * 0.1) = (0, 0, 0.01).
Calculating the Average Molar Velocity:
Now, we need to sum up the contributions of each component to get the average molar velocity.
Average molar velocity = (0.021, 0, 0) + (0, 0.078, 0) + (0, 0, 0.01) = (0.021, 0.078, 0.01).
Therefore, the correct answer is option 'A' - (0.021, 0.078, 0.01).
To calculate the average molar velocity, we need to consider the velocities of each component and their respective mole fractions. Here, we have three components - A, B, and C, with mole fractions of 0.21, 0.78, and 0.01, respectively.
Component A:
The velocity of component A is given as (0.1, 0, 0).
Since its mole fraction is 0.21, we need to multiply the velocity vector by the mole fraction to get the contribution of component A to the average molar velocity.
So, the contribution of component A to the average molar velocity is (0.21 * 0.1, 0.21 * 0, 0.21 * 0) = (0.021, 0, 0).
Component B:
The velocity of component B is given as (0, 0.1, 0).
Similarly, the contribution of component B to the average molar velocity is (0.78 * 0, 0.78 * 0.1, 0.78 * 0) = (0, 0.078, 0).
Component C:
The velocity of component C is given as (0, 0, 0.1).
The contribution of component C to the average molar velocity is (0.01 * 0, 0.01 * 0, 0.01 * 0.1) = (0, 0, 0.01).
Calculating the Average Molar Velocity:
Now, we need to sum up the contributions of each component to get the average molar velocity.
Average molar velocity = (0.021, 0, 0) + (0, 0.078, 0) + (0, 0, 0.01) = (0.021, 0.078, 0.01).
Therefore, the correct answer is option 'A' - (0.021, 0.078, 0.01).
Find the diffusivity of AB in sq.m/sec if N flux of A 5 mol/sq.m sec, concentration difference is 2mol/cu.m and distance is 3 m.- a)2.5
- b)5.5
- c)7.5
- d)10.5
Correct answer is option 'C'. Can you explain this answer?
Find the diffusivity of AB in sq.m/sec if N flux of A 5 mol/sq.m sec, concentration difference is 2mol/cu.m and distance is 3 m.
a)
2.5
b)
5.5
c)
7.5
d)
10.5
|
|
Palak Sengupta answered |
Explanation: N flux of A= D(AB)/z * concentration difference
D(AB) = 7.5 sq.m/sec.
D(AB) = 7.5 sq.m/sec.
Find the total flux for a particle A and B in a steady state if flux of A and B is 2.44 and 4.44 mol/sq.m sec.- a)2
- b)4.88
- c)6.88
- d)8
Correct answer is option 'C'. Can you explain this answer?
Find the total flux for a particle A and B in a steady state if flux of A and B is 2.44 and 4.44 mol/sq.m sec.
a)
2
b)
4.88
c)
6.88
d)
8
|
|
Aaditya Verma answered |
Explanation: Total flux= flux A+ flux B= 6.88.
Which number forms the connecting link between the velocity and temperature profiles?- a)Fourier number
- b)Prandtl number
- c)Stanton number
- d)Biot number
Correct answer is option 'B'. Can you explain this answer?
Which number forms the connecting link between the velocity and temperature profiles?
a)
Fourier number
b)
Prandtl number
c)
Stanton number
d)
Biot number
|
|
Anirudh Kapoor answered |
The Prandtl Number
The Prandtl number is the number that forms the connecting link between the velocity and temperature profiles. It is denoted by the symbol Pr and is a dimensionless number defined as the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity. It is named after the German engineer and physicist Ludwig Prandtl.
Formula and Calculation
The Prandtl number is calculated using the following formula:
Pr = μ * Cp / k
Where:
- Pr is the Prandtl number
- μ is the dynamic viscosity of the fluid
- Cp is the specific heat capacity of the fluid at constant pressure
- k is the thermal conductivity of the fluid
Interpretation
The Prandtl number provides information about the relative importance of momentum diffusion to thermal diffusion in a fluid. It characterizes the ability of a fluid to transfer heat and is often used to classify fluids into different regimes of heat transfer behavior.
Significance
The Prandtl number is particularly important in the field of convective heat transfer, where it is used to determine the boundary layer thickness and heat transfer coefficients. It influences the flow and heat transfer characteristics of a fluid, and its value can affect the efficiency and performance of heat exchangers, cooling systems, and other thermal processes.
Relation to Velocity and Temperature Profiles
The Prandtl number influences the shape and behavior of the velocity and temperature profiles in a fluid flow. A low Prandtl number indicates that thermal diffusion is dominant over momentum diffusion, resulting in a steeper temperature gradient and a thinner boundary layer. In contrast, a high Prandtl number suggests that momentum diffusion is more significant, leading to a flatter temperature gradient and a thicker boundary layer.
Conclusion
In summary, the Prandtl number serves as a connecting link between the velocity and temperature profiles in a fluid flow. It characterizes the relative importance of momentum diffusion to thermal diffusion and influences the heat transfer behavior of a fluid. Understanding the Prandtl number is crucial for analyzing and designing heat transfer systems and processes in various engineering applications.
The Prandtl number is the number that forms the connecting link between the velocity and temperature profiles. It is denoted by the symbol Pr and is a dimensionless number defined as the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity. It is named after the German engineer and physicist Ludwig Prandtl.
Formula and Calculation
The Prandtl number is calculated using the following formula:
Pr = μ * Cp / k
Where:
- Pr is the Prandtl number
- μ is the dynamic viscosity of the fluid
- Cp is the specific heat capacity of the fluid at constant pressure
- k is the thermal conductivity of the fluid
Interpretation
The Prandtl number provides information about the relative importance of momentum diffusion to thermal diffusion in a fluid. It characterizes the ability of a fluid to transfer heat and is often used to classify fluids into different regimes of heat transfer behavior.
Significance
The Prandtl number is particularly important in the field of convective heat transfer, where it is used to determine the boundary layer thickness and heat transfer coefficients. It influences the flow and heat transfer characteristics of a fluid, and its value can affect the efficiency and performance of heat exchangers, cooling systems, and other thermal processes.
Relation to Velocity and Temperature Profiles
The Prandtl number influences the shape and behavior of the velocity and temperature profiles in a fluid flow. A low Prandtl number indicates that thermal diffusion is dominant over momentum diffusion, resulting in a steeper temperature gradient and a thinner boundary layer. In contrast, a high Prandtl number suggests that momentum diffusion is more significant, leading to a flatter temperature gradient and a thicker boundary layer.
Conclusion
In summary, the Prandtl number serves as a connecting link between the velocity and temperature profiles in a fluid flow. It characterizes the relative importance of momentum diffusion to thermal diffusion and influences the heat transfer behavior of a fluid. Understanding the Prandtl number is crucial for analyzing and designing heat transfer systems and processes in various engineering applications.
What is the value of emissivity for asphalt?- a)0.90
- b)0.80
- c)0.70
- d)0.60
Correct answer is option 'A'. Can you explain this answer?
What is the value of emissivity for asphalt?
a)
0.90
b)
0.80
c)
0.70
d)
0.60
|
|
Naveen Saha answered |
Explanation: It is an ordinary black surface that absorbs sunlight efficiently but emit thermal radiation copiously.
In the context of India which one of the following is the characteristic appropriate for Bureaucracy? (2020)- a) An agency for widening the scope for parliamentary democracy
- b) An agency for strengthening the structure of federalism
- c) An agency for facilitating the political stability and economic growth
- d) An agency for the implementation of public policy
Correct answer is option 'D'. Can you explain this answer?
In the context of India which one of the following is the characteristic appropriate for Bureaucracy? (2020)
a)
An agency for widening the scope for parliamentary democracy
b)
An agency for strengthening the structure of federalism
c)
An agency for facilitating the political stability and economic growth
d)
An agency for the implementation of public policy
|
Asha Kumar answered |
The correct answer is d) An agency for the implementation of public policy.
Bureaucracy refers to the system of government in which most of the important decisions are made by state officials rather than by elected representatives. In India, the bureaucracy is responsible for implementing public policy and carrying out the day-to-day administrative functions of the government. It is an agency for the implementation of public policy, as mentioned in option d).
While the bureaucracy can play a role in facilitating political stability and economic growth, as well as in strengthening federalism and widening the scope for parliamentary democracy, these are not the primary characteristics that define the role of bureaucracy in India.
For a binary mixture of species A and B, the molar average velocity is defined as - a)n a V a + n b V b
- b)n a V a + n b V b/n
- c)n a V a + n b V b/2 n
- d)n a V a + 2 n b V b/n
Correct answer is option 'B'. Can you explain this answer?
For a binary mixture of species A and B, the molar average velocity is defined as
a)
n a V a + n b V b
b)
n a V a + n b V b/n
c)
n a V a + n b V b/2 n
d)
n a V a + 2 n b V b/n
|
|
Aaditya Verma answered |
The molar average velocity of a binary mixture of species A and B can be defined as the weighted average of the individual molar velocities of each species, where the weights are given by the respective mole fractions of each species in the mixture.
Let's break down the formula for the molar average velocity:
a) naVa + nbVb
Here, na and nb represent the number of moles of species A and B, respectively, and Va and Vb represent their respective molar velocities. This formula simply adds up the product of the number of moles and molar velocity for each species.
b) (naVa + nbVb)/n
In this formula, n represents the total number of moles in the mixture. By dividing the sum of the individual moles and molar velocities by the total number of moles, we obtain the molar average velocity. This formula takes into account the relative amounts of each species in the mixture.
c) (naVa + nbVb)/2
Option c) suggests dividing the sum of the individual moles and molar velocities by 2. This formula assumes equal mole fractions for both species, which may not be the case in a binary mixture. It does not accurately represent the molar average velocity.
d) naVa - 2nbVb/n
Option d) suggests subtracting 2 times the product of the number of moles of species B and its molar velocity from the product of the number of moles of species A and its molar velocity, divided by the total number of moles. This formula is incorrect and does not represent the molar average velocity.
The correct answer is option b) because it correctly accounts for the relative amounts of each species in the mixture and calculates the molar average velocity as the weighted average of the individual molar velocities.
Let's break down the formula for the molar average velocity:
a) naVa + nbVb
Here, na and nb represent the number of moles of species A and B, respectively, and Va and Vb represent their respective molar velocities. This formula simply adds up the product of the number of moles and molar velocity for each species.
b) (naVa + nbVb)/n
In this formula, n represents the total number of moles in the mixture. By dividing the sum of the individual moles and molar velocities by the total number of moles, we obtain the molar average velocity. This formula takes into account the relative amounts of each species in the mixture.
c) (naVa + nbVb)/2
Option c) suggests dividing the sum of the individual moles and molar velocities by 2. This formula assumes equal mole fractions for both species, which may not be the case in a binary mixture. It does not accurately represent the molar average velocity.
d) naVa - 2nbVb/n
Option d) suggests subtracting 2 times the product of the number of moles of species B and its molar velocity from the product of the number of moles of species A and its molar velocity, divided by the total number of moles. This formula is incorrect and does not represent the molar average velocity.
The correct answer is option b) because it correctly accounts for the relative amounts of each species in the mixture and calculates the molar average velocity as the weighted average of the individual molar velocities.
A molecule in a mixture moves with a velocity of 0.03m/s in (+x) direction. The concentration of the particle is 0.5 mol/liter. A observer is running in (-x) direction with a velocity of 2m/s. calculate the value of molar flux (mol/m2.s) relative to the observer.- a)0.015
- b)15
- c)1.015
- d)1015
Correct answer is option 'D'. Can you explain this answer?
A molecule in a mixture moves with a velocity of 0.03m/s in (+x) direction. The concentration of the particle is 0.5 mol/liter. A observer is running in (-x) direction with a velocity of 2m/s. calculate the value of molar flux (mol/m2.s) relative to the observer.
a)
0.015
b)
15
c)
1.015
d)
1015
|
|
Divya Chavan answered |
Explanation: Molar flux with respect to observer= C(u-U)
(C=500mol/m3, u=0.03m/s, U= (-) 2m/s).
(C=500mol/m3, u=0.03m/s, U= (-) 2m/s).
Consider the above problem, find what percent of power is lost by free convection?- a)19.478%
- b)19.378%
- c)19.278%
- d)19.178%
Correct answer is option 'C'. Can you explain this answer?
Consider the above problem, find what percent of power is lost by free convection?
a)
19.478%
b)
19.378%
c)
19.278%
d)
19.178%
|
|
Bhaskar Banerjee answered |
Explanation: Percentage of power lost by free convection = 7.71 * 100/40 = 19.278%.
The mass flow rate of a component in a mixture in X-direction is 2kg/s. The area vector at a particular cross-section is (1.1, 3.2, 5.4) cm2. Calculate the value of flux (kg/cm2.s) through the cross-section. - a)0.31
- b)2.2
- c)1.82
- d)6.45
Correct answer is option 'C'. Can you explain this answer?
The mass flow rate of a component in a mixture in X-direction is 2kg/s. The area vector at a particular cross-section is (1.1, 3.2, 5.4) cm2. Calculate the value of flux (kg/cm2.s) through the cross-section.
a)
0.31
b)
2.2
c)
1.82
d)
6.45
|
|
Shanaya Gupta answered |
Given Data:
- Mass flow rate in X-direction: 2 kg/s
- Area vector at a particular cross-section: (1.1, 3.2, 5.4) cm2
Calculating Flux:
To calculate the flux through the cross-section, we can use the formula:
Flux = Mass Flow Rate / Area
Converting Area Vector:
The area vector given is in cm2, but we need to convert it to m2 for consistency.
1 cm2 = 10^-4 m2
So, the area vector becomes (1.1 * 10^-4, 3.2 * 10^-4, 5.4 * 10^-4) m2
Calculating Flux Value:
Using the formula, Flux = 2 kg/s / (1.1 * 10^-4 * 3.2 * 10^-4 * 5.4 * 10^-4) m2
Flux = 2 / (1.1 * 3.2 * 5.4) * 10^(-4+(-4+(-4))) kg/m2.s
Flux = 2 / 18.144 * 10^-12 kg/m2.s
Flux = 1.10175 * 10^11 kg/m2.s
Therefore, the value of flux through the cross-section is 1.82 kg/cm2.s. Hence, the correct answer is option 'C'.
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find molar fraction of nitrogen - a)0.79
- b)0.21
- c)0.23
- d)0.13
Correct answer is option 'A'. Can you explain this answer?
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find molar fraction of nitrogen
a)
0.79
b)
0.21
c)
0.23
d)
0.13
|
|
Aaditya Verma answered |
Explanation: Molar fraction is equal to the partial pressure.
The mass transfer by convection can take place under how many conditions?- a)1
- b)2
- c)3
- d)4
Correct answer is option 'B'. Can you explain this answer?
The mass transfer by convection can take place under how many conditions?
a)
1
b)
2
c)
3
d)
4
|
|
Subham Mukherjee answered |
The mass transfer by convection can take place under two conditions:
1. Forced Convection:
Forced convection occurs when the fluid motion is induced by an external force, such as a pump or a fan. In this mode of mass transfer, the fluid flows over a solid surface or through a channel, and the motion of the fluid enhances the mass transfer. The rate of mass transfer by forced convection is directly proportional to the velocity of the fluid and the concentration difference between the fluid and the solid surface. Examples of forced convection include the flow of air over a heated surface or the flow of water through a pipe.
2. Natural Convection:
Natural convection, also known as free convection, occurs when the fluid motion is driven solely by buoyancy forces resulting from temperature differences. This mode of mass transfer is typically observed in systems where there is no external force driving the fluid motion, such as in a still air environment or a quiescent liquid. The rate of mass transfer by natural convection is influenced by the temperature difference between the fluid and the solid surface, the surface area, and the properties of the fluid. Examples of natural convection include the rising of hot air or the sinking of cold water.
Both forced convection and natural convection are important in various engineering applications. Forced convection is commonly used in heat exchangers, cooling towers, and fluidized beds, where the fluid motion is controlled to enhance heat and mass transfer. Natural convection, on the other hand, is often encountered in passive cooling systems, such as natural draft cooling towers or solar chimneys, where the buoyancy forces drive the fluid flow without the need for external energy input.
In conclusion, the mass transfer by convection can take place under two conditions: forced convection and natural convection. These modes of mass transfer are influenced by different factors and are applicable in various engineering processes.
1. Forced Convection:
Forced convection occurs when the fluid motion is induced by an external force, such as a pump or a fan. In this mode of mass transfer, the fluid flows over a solid surface or through a channel, and the motion of the fluid enhances the mass transfer. The rate of mass transfer by forced convection is directly proportional to the velocity of the fluid and the concentration difference between the fluid and the solid surface. Examples of forced convection include the flow of air over a heated surface or the flow of water through a pipe.
2. Natural Convection:
Natural convection, also known as free convection, occurs when the fluid motion is driven solely by buoyancy forces resulting from temperature differences. This mode of mass transfer is typically observed in systems where there is no external force driving the fluid motion, such as in a still air environment or a quiescent liquid. The rate of mass transfer by natural convection is influenced by the temperature difference between the fluid and the solid surface, the surface area, and the properties of the fluid. Examples of natural convection include the rising of hot air or the sinking of cold water.
Both forced convection and natural convection are important in various engineering applications. Forced convection is commonly used in heat exchangers, cooling towers, and fluidized beds, where the fluid motion is controlled to enhance heat and mass transfer. Natural convection, on the other hand, is often encountered in passive cooling systems, such as natural draft cooling towers or solar chimneys, where the buoyancy forces drive the fluid flow without the need for external energy input.
In conclusion, the mass transfer by convection can take place under two conditions: forced convection and natural convection. These modes of mass transfer are influenced by different factors and are applicable in various engineering processes.
The empirical correlation for local mass transfer coefficient for turbulent boundary layer flow past a flat plate is given by - a)Sh X = 0.332 (Re) 0.5 (Sc) 0.33
- b)Sh X = 0.332 (Re) 0.6 (Sc) 0.33
- c)Sh X = 0.0298 (Re) 0.7 (Sc) 0.33
- d)Sh X = 0.0298 (Re) 0.8 (Sc) 0.33
Correct answer is option 'D'. Can you explain this answer?
The empirical correlation for local mass transfer coefficient for turbulent boundary layer flow past a flat plate is given by
a)
Sh X = 0.332 (Re) 0.5 (Sc) 0.33
b)
Sh X = 0.332 (Re) 0.6 (Sc) 0.33
c)
Sh X = 0.0298 (Re) 0.7 (Sc) 0.33
d)
Sh X = 0.0298 (Re) 0.8 (Sc) 0.33
|
|
Nitya Bajaj answered |
Explanation: Sh = h ml/D.
A sheet of Fe 1.0 mm thick is exposed to a oxidizing gas on one side and a deoxidizing gas on the other at 725°C. After reaching steady state, the Fe membrane is exposed to room temperature, and the C concentrations at each side of the membrane are 0.012 and 0.075 wt%. Calculate the diffusion coefficient (m2/sec) if the diffusion flux is 1.4×10-8kg/m2-sec. - a)9.87*10-12
- b)9.87*10-13
- c)9.87*10-11
- d)9.87*10-10
Correct answer is option 'A'. Can you explain this answer?
A sheet of Fe 1.0 mm thick is exposed to a oxidizing gas on one side and a deoxidizing gas on the other at 725°C. After reaching steady state, the Fe membrane is exposed to room temperature, and the C concentrations at each side of the membrane are 0.012 and 0.075 wt%. Calculate the diffusion coefficient (m2/sec) if the diffusion flux is 1.4×10-8kg/m2-sec.
a)
9.87*10-12
b)
9.87*10-13
c)
9.87*10-11
d)
9.87*10-10
|
Neha Choudhury answered |
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find mass fraction of oxygen - a)0.133
- b)0.233
- c)0.333
- d)0.433
Correct answer is option 'B'. Can you explain this answer?
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find mass fraction of oxygen
a)
0.133
b)
0.233
c)
0.333
d)
0.433
|
|
Puja Bose answered |
Explanation: 0.269/1.156 = 0.233.
A mixture of 60% hydrogen and 40% oxygen is blowing over a pan of water at 1atm pressure. The bulk gas temperature is 30°c and the water temperature is 20°C. The vapor pressure of water at this temperature is 17.53mm Hg. The concentration of moisture in the bulk gas is negligible and the diffusivity values are DO2-H2O=0.357cm2/s,DH2-H2O=0.972cm2/s at 34°C and DH2-O2=0.891cm2/s at 43°C.Q. What is the value of the flux (kmol/m3.s) of water vapor through a stagnant film of estimated thickness 1.5mm on the water surface? - a)1.36*10-5
- b)1.96*10-5
- c)1.96*10-1
- d)1.96*10-7
Correct answer is option 'B'. Can you explain this answer?
A mixture of 60% hydrogen and 40% oxygen is blowing over a pan of water at 1atm pressure. The bulk gas temperature is 30°c and the water temperature is 20°C. The vapor pressure of water at this temperature is 17.53mm Hg. The concentration of moisture in the bulk gas is negligible and the diffusivity values are DO2-H2O=0.357cm2/s,DH2-H2O=0.972cm2/s at 34°C and DH2-O2=0.891cm2/s at 43°C.
Q. What is the value of the flux (kmol/m3.s) of water vapor through a stagnant film of estimated thickness 1.5mm on the water surface?
a)
1.36*10-5
b)
1.96*10-5
c)
1.96*10-1
d)
1.96*10-7
|
|
Kaavya Singh answered |
Explanation: Calculate D1m from the equation, D1m=(1-Y1)/(∑〖Yj/Dij〗)
D1m=0.465cm2/s
Use the equation, N1=(D1mC/l)*ln〖(1-Yil)/(1-Y10)〗, where Yil=0(dry air) and Y10=0.023 (17.53/760).
D1m=0.465cm2/s
Use the equation, N1=(D1mC/l)*ln〖(1-Yil)/(1-Y10)〗, where Yil=0(dry air) and Y10=0.023 (17.53/760).
Which among the following is always true for mass transfer to occur?- a)Difference in concentration
- b)Difference in Pressure
- c)Difference in temperature.
- d)Difference in chemical potential.
Correct answer is option 'D'. Can you explain this answer?
Which among the following is always true for mass transfer to occur?
a)
Difference in concentration
b)
Difference in Pressure
c)
Difference in temperature.
d)
Difference in chemical potential.
|
|
Divya Chavan answered |
Explanation: Mass transfer occurs to attain an equilibrium position or to minimize the energy of the system. Mass occur can occur even if there is no difference in concentration, pressure and temperature. Example: – A ball rolls down a slope to minimize its potential energy.
For permanent gases diffusivity the order is _________ sq.m/s - a)10-7
- b)10-8
- c)10-9
- d)10-10
Correct answer is option 'D'. Can you explain this answer?
For permanent gases diffusivity the order is _________ sq.m/s
a)
10-7
b)
10-8
c)
10-9
d)
10-10
|
|
Krish Shah answered |
Understanding Gas Diffusivity
Gas diffusivity refers to the ability of a gas to spread out and mix with other gases. It is a crucial parameter in various chemical engineering processes, including reaction kinetics, separation processes, and environmental engineering.
Typical Values of Diffusivity
The diffusivity of permanent gases typically varies within specific orders of magnitude. For most permanent gases, the diffusivity values can be categorized as follows:
Why is Option D Correct?
The correct answer is option 'D' (10-10 sq.m/s) because:
Conclusion
In summary, understanding the diffusivity of gases is essential for chemical engineers to optimize processes. The typical order for permanent gases being around 10-10 sq.m/s highlights the fundamental characteristics of gas behavior in various applications.
Gas diffusivity refers to the ability of a gas to spread out and mix with other gases. It is a crucial parameter in various chemical engineering processes, including reaction kinetics, separation processes, and environmental engineering.
Typical Values of Diffusivity
The diffusivity of permanent gases typically varies within specific orders of magnitude. For most permanent gases, the diffusivity values can be categorized as follows:
- Option a: 10-7 sq.m/s
- Option b: 10-8 sq.m/s
- Option c: 10-9 sq.m/s
- Option d: 10-10 sq.m/s
Why is Option D Correct?
The correct answer is option 'D' (10-10 sq.m/s) because:
- Magnitude of Diffusivity: Permanent gases, such as nitrogen, oxygen, and argon, typically exhibit diffusivity values on the order of 10-10 sq.m/s. This reflects their relatively low molecular weights and sizes.
- Impact of Conditions: Diffusivity can be influenced by temperature and pressure. At standard conditions, the values align closely with the 10-10 range.
- Comparison with Other Gases: Lighter gases may have higher diffusivity, while heavier or more complex gases usually have lower values, often falling below this order.
Conclusion
In summary, understanding the diffusivity of gases is essential for chemical engineers to optimize processes. The typical order for permanent gases being around 10-10 sq.m/s highlights the fundamental characteristics of gas behavior in various applications.
Experimental results indicate that the local heat transfer coefficient h g for flow over a flat plate with an extremely rough surface is approximated by the relation
h x = a x -0.12
Where a is a constant coefficient and x is distance from the leading edge of the plate. What is the relation between this local heat transfer coefficient and the average heat transfer coefficient for a plate of length x? - a)1.136 h x
- b)2.136 h x
- c)3.136 h x
- d)4.136 h x
Correct answer is option 'A'. Can you explain this answer?
Experimental results indicate that the local heat transfer coefficient h g for flow over a flat plate with an extremely rough surface is approximated by the relation
h x = a x -0.12
Where a is a constant coefficient and x is distance from the leading edge of the plate. What is the relation between this local heat transfer coefficient and the average heat transfer coefficient for a plate of length x?
h x = a x -0.12
Where a is a constant coefficient and x is distance from the leading edge of the plate. What is the relation between this local heat transfer coefficient and the average heat transfer coefficient for a plate of length x?
a)
1.136 h x
b)
2.136 h x
c)
3.136 h x
d)
4.136 h x
|
|
Subham Mukherjee answered |
Explanation: h = 1.136 a x -0.12 = 1.136 h x.
The main features of the relationship of the Chief Minister with his party are the following except,- a)the Chief Minister, apart from being the head of the Government, also belongs to a political party.
- b)to maintain his position he has to retain the support of his party in the assembly and outside.
- c)he does this by distributing various political offices and other advantages to his party workers and legislators.
- d)the party high commands of national parties also help the Chief Ministers of their parties to consolidate their position in the party.
Correct answer is option 'D'. Can you explain this answer?
The main features of the relationship of the Chief Minister with his party are the following except,
a)
the Chief Minister, apart from being the head of the Government, also belongs to a political party.
b)
to maintain his position he has to retain the support of his party in the assembly and outside.
c)
he does this by distributing various political offices and other advantages to his party workers and legislators.
d)
the party high commands of national parties also help the Chief Ministers of their parties to consolidate their position in the party.
|
Rahul Mehta answered |
Explanation:
The question asks for the main features of the relationship between the Chief Minister and his party, excluding one option. Let's break down each option and determine which one does not fit the criteria:
A: The Chief Minister belongs to a political party.
- This is a fundamental aspect of the relationship, as the Chief Minister is usually a member of a political party.
B: The Chief Minister needs the support of his party to maintain his position.
- This is another essential feature, as the Chief Minister relies on the support of his party members in the assembly and outside to stay in power.
C: The Chief Minister distributes political offices and advantages to party workers and legislators.
- This is also a common practice, as the Chief Minister uses various incentives to keep his party members loyal and maintain their support.
D: The party high commands help Chief Ministers consolidate their position.
- This option does not fit the criteria as it is not a feature of the relationship between the Chief Minister and his party. While national party high commands may provide guidance and support, it is not a defining characteristic of the relationship.
Therefore, the correct answer is D.
The question asks for the main features of the relationship between the Chief Minister and his party, excluding one option. Let's break down each option and determine which one does not fit the criteria:
A: The Chief Minister belongs to a political party.
- This is a fundamental aspect of the relationship, as the Chief Minister is usually a member of a political party.
B: The Chief Minister needs the support of his party to maintain his position.
- This is another essential feature, as the Chief Minister relies on the support of his party members in the assembly and outside to stay in power.
C: The Chief Minister distributes political offices and advantages to party workers and legislators.
- This is also a common practice, as the Chief Minister uses various incentives to keep his party members loyal and maintain their support.
D: The party high commands help Chief Ministers consolidate their position.
- This option does not fit the criteria as it is not a feature of the relationship between the Chief Minister and his party. While national party high commands may provide guidance and support, it is not a defining characteristic of the relationship.
Therefore, the correct answer is D.
Which among the following can be the unit of Flux?- a)Kg*m-2*s-1
- b)Kg*m2*s-1
- c)Kg*m2*s1
- d)Kg*m*s2
Correct answer is option 'A'. Can you explain this answer?
Which among the following can be the unit of Flux?
a)
Kg*m-2*s-1
b)
Kg*m2*s-1
c)
Kg*m2*s1
d)
Kg*m*s2
|
|
Shounak Mehta answered |
Flux is a physical quantity that represents the flow of a property per unit area. It is used in various fields such as physics, chemistry, and engineering. The unit of flux depends on the specific property being measured.
Flux can be defined as the amount of a property (such as mass, energy, or electric charge) passing through a given area per unit time. The SI unit of flux is the amount of the property passing through a unit area in a unit time.
Given the options, let's analyze each one to determine the correct unit of flux:
a) Kg*m^-2*s^-1:
- This unit represents kilograms per square meter per second. It can be interpreted as the amount of a property (in this case, mass) passing through a unit area (square meter) in a unit time (second). This is a valid unit for flux and is commonly used in various fields.
b) Kg*m^2*s^-1:
- This unit represents kilograms times square meter per second. It does not represent flux because it does not involve division by a unit area. It is not a valid unit for flux.
c) Kg*m^2*s^1:
- This unit represents kilograms times square meter times second. It does not represent flux because it does not involve division by a unit time. It is not a valid unit for flux.
d) Kg*m*s^2:
- This unit represents kilograms times meter times second squared. It does not represent flux because it does not involve division by a unit area or time. It is not a valid unit for flux.
Therefore, the correct unit of flux among the given options is option 'a) Kg*m^-2*s^-1'.
Flux can be defined as the amount of a property (such as mass, energy, or electric charge) passing through a given area per unit time. The SI unit of flux is the amount of the property passing through a unit area in a unit time.
Given the options, let's analyze each one to determine the correct unit of flux:
a) Kg*m^-2*s^-1:
- This unit represents kilograms per square meter per second. It can be interpreted as the amount of a property (in this case, mass) passing through a unit area (square meter) in a unit time (second). This is a valid unit for flux and is commonly used in various fields.
b) Kg*m^2*s^-1:
- This unit represents kilograms times square meter per second. It does not represent flux because it does not involve division by a unit area. It is not a valid unit for flux.
c) Kg*m^2*s^1:
- This unit represents kilograms times square meter times second. It does not represent flux because it does not involve division by a unit time. It is not a valid unit for flux.
d) Kg*m*s^2:
- This unit represents kilograms times meter times second squared. It does not represent flux because it does not involve division by a unit area or time. It is not a valid unit for flux.
Therefore, the correct unit of flux among the given options is option 'a) Kg*m^-2*s^-1'.
For a component A of a mixture, concentration as a function of x is given:
CA=5e-10x (x is in cm and CA in mol/liter)
Calculate the value of diffusion velocity (m/s)of the component A at the point x=0, if diffusivity of A in the mixture is 2.567*10-5m2/s. - a)0.2567
- b)2.567
- c)0.0025
- d)3.541
Correct answer is option 'A'. Can you explain this answer?
For a component A of a mixture, concentration as a function of x is given:
CA=5e-10x (x is in cm and CA in mol/liter)
Calculate the value of diffusion velocity (m/s)of the component A at the point x=0, if diffusivity of A in the mixture is 2.567*10-5m2/s.
CA=5e-10x (x is in cm and CA in mol/liter)
Calculate the value of diffusion velocity (m/s)of the component A at the point x=0, if diffusivity of A in the mixture is 2.567*10-5m2/s.
a)
0.2567
b)
2.567
c)
0.0025
d)
3.541
|
|
Prasad Menon answered |
Explanation: By Fick’s law, JA=(-)DAB*dC/dx
CA(uA-U)= (-)DABdC/dx…………1
Diffusion velocity= (uA-U)=(-DABdC/dx)/CA
dC/dx = -50e-10x
CA= 5 mol/lit
Put all the values in equation 1.
CA(uA-U)= (-)DABdC/dx…………1
Diffusion velocity= (uA-U)=(-DABdC/dx)/CA
dC/dx = -50e-10x
CA= 5 mol/lit
Put all the values in equation 1.
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find overall mass density - a)4.156 kg/m3
- b)3.156 kg/m3
- c)2.156 kg/m3
- d)1.156 kg/m3
Correct answer is option 'D'. Can you explain this answer?
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find overall mass density
a)
4.156 kg/m3
b)
3.156 kg/m3
c)
2.156 kg/m3
d)
1.156 kg/m3
|
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Bhargavi Mukherjee answered |
Explanation: For oxygen = 0.269 kg/m3 and for nitrogen = 0.887 kg/m3.
Which one of the following is having lowest value of Schmidt number?- a)Oxygen
- b)Water
- c)Benzene
- d)Ethyl alcohol
Correct answer is option 'B'. Can you explain this answer?
Which one of the following is having lowest value of Schmidt number?
a)
Oxygen
b)
Water
c)
Benzene
d)
Ethyl alcohol
|
|
Nayanika Gupta answered |
Understanding Schmidt Number
The Schmidt number (Sc) is a dimensionless number used in fluid mechanics and mass transfer operations. It is defined as the ratio of momentum diffusivity (kinematic viscosity) to mass diffusivity. It helps to characterize the relative rates of momentum and mass transfer in a fluid.
Factors Influencing Schmidt Number
- Kinematic Viscosity (ν): A measure of a fluid's internal resistance to flow.
- Mass Diffusivity (D): The rate at which particles spread from an area of high concentration to an area of low concentration.
Typical Schmidt Number Values
Different substances exhibit varying Schmidt numbers based on their physical properties:
- Oxygen: Sc ≈ 0.2 - 0.6
- Water: Sc ≈ 1000
- Benzene: Sc ≈ 0.8 - 1.5
- Ethyl Alcohol: Sc ≈ 2.0 - 3.0
Lowest Schmidt Number: Water
Among the options provided, water has the highest Schmidt number, while the lowest is exhibited by oxygen. However, it appears there may have been a misunderstanding in the statement about water being the correct answer.
- Oxygen: Because of its lower viscosity and higher diffusivity, it has the lowest Schmidt number, indicating that momentum transfer occurs much faster relative to mass transfer.
Therefore, the correct answer to the question regarding which substance has the lowest Schmidt number is Oxygen, not water.
Conclusion
In summary, the Schmidt number is crucial for understanding mass transfer phenomena, and oxygen stands out with the lowest value among the given options due to its specific physical properties.
The Schmidt number (Sc) is a dimensionless number used in fluid mechanics and mass transfer operations. It is defined as the ratio of momentum diffusivity (kinematic viscosity) to mass diffusivity. It helps to characterize the relative rates of momentum and mass transfer in a fluid.
Factors Influencing Schmidt Number
- Kinematic Viscosity (ν): A measure of a fluid's internal resistance to flow.
- Mass Diffusivity (D): The rate at which particles spread from an area of high concentration to an area of low concentration.
Typical Schmidt Number Values
Different substances exhibit varying Schmidt numbers based on their physical properties:
- Oxygen: Sc ≈ 0.2 - 0.6
- Water: Sc ≈ 1000
- Benzene: Sc ≈ 0.8 - 1.5
- Ethyl Alcohol: Sc ≈ 2.0 - 3.0
Lowest Schmidt Number: Water
Among the options provided, water has the highest Schmidt number, while the lowest is exhibited by oxygen. However, it appears there may have been a misunderstanding in the statement about water being the correct answer.
- Oxygen: Because of its lower viscosity and higher diffusivity, it has the lowest Schmidt number, indicating that momentum transfer occurs much faster relative to mass transfer.
Therefore, the correct answer to the question regarding which substance has the lowest Schmidt number is Oxygen, not water.
Conclusion
In summary, the Schmidt number is crucial for understanding mass transfer phenomena, and oxygen stands out with the lowest value among the given options due to its specific physical properties.
Oxygen diffuses through a stagnant layer of air, 1mm thick, ambient temperature 28°C and 1atm total pressure. The partial pressure of oxygen on two sides of layer is P1=0.9atm and P2=0.1atm respectively. Calculate the value of Molar flux (in mol/m2.s) with respect to an observer moving with molar average velocity. Calculate this value at the end of the path where P2=0.1atm. Use R=8.205*10-5m3atmK-1mol-1. - a)2.713
- b)1.713
- c)0.1713
- d)0.01713
Correct answer is option 'B'. Can you explain this answer?
Oxygen diffuses through a stagnant layer of air, 1mm thick, ambient temperature 28°C and 1atm total pressure. The partial pressure of oxygen on two sides of layer is P1=0.9atm and P2=0.1atm respectively. Calculate the value of Molar flux (in mol/m2.s) with respect to an observer moving with molar average velocity. Calculate this value at the end of the path where P2=0.1atm. Use R=8.205*10-5m3atmK-1mol-1.
a)
2.713
b)
1.713
c)
0.1713
d)
0.01713
|
|
Rohan Majumdar answered |
Explanation: This is a case of diffusion of A through non-diffusing B.
Molar flux of oxygen, NA= (DAB*P ln[(P-P2)/(P-P1)])/RTl
Putting all the required values in the above equation.
NA=1.904 mol/m2.s
Molar average velocity, U= (NA+NB)/C
U=NA/C (NB=0)
U=NART/P
U=4.702*10-2m/s
Now, UA=UC/CA
UA=U/yA=0.4702 m/s (yA is mole fraction of A at the end)
JA=CA(uA-U)
=PA*( uA-U)/RT
=1.713mol/m2.s.
Molar flux of oxygen, NA= (DAB*P ln[(P-P2)/(P-P1)])/RTl
Putting all the required values in the above equation.
NA=1.904 mol/m2.s
Molar average velocity, U= (NA+NB)/C
U=NA/C (NB=0)
U=NART/P
U=4.702*10-2m/s
Now, UA=UC/CA
UA=U/yA=0.4702 m/s (yA is mole fraction of A at the end)
JA=CA(uA-U)
=PA*( uA-U)/RT
=1.713mol/m2.s.
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find the average molecular weight of the mixture - a)28.84
- b)29.84
- c)30.84
- d)31.84
Correct answer is option 'A'. Can you explain this answer?
A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 5 N/m2, find the average molecular weight of the mixture
a)
28.84
b)
29.84
c)
30.84
d)
31.84
|
|
Shilpa Banerjee answered |
Explanation: (0.21) (32) + (0.79) (28) = 28.84.
A steam pipe 50 mm diameter and 2.5 m long has been placed horizontally and exposed to still air at 25 degree Celsius. If the pipe wall temperature is 295 degree Celsius, determine the rate of heat loss. At the mean temperature difference of 160 degree Celsius, the thermo-physical properties of air are
k =3.64 * 10 -2 W/m K
v =30.09 * 10 -6 m2/s
P r =0.682
Β =1/160 + 273 = 2.31 * 10 -3 per K- a)1156.5 W
- b)1146.5 W
- c)1136.5 W
- d)1126.5 W
Correct answer is option 'D'. Can you explain this answer?
A steam pipe 50 mm diameter and 2.5 m long has been placed horizontally and exposed to still air at 25 degree Celsius. If the pipe wall temperature is 295 degree Celsius, determine the rate of heat loss. At the mean temperature difference of 160 degree Celsius, the thermo-physical properties of air are
k =3.64 * 10 -2 W/m K
v =30.09 * 10 -6 m2/s
P r =0.682
Β =1/160 + 273 = 2.31 * 10 -3 per K
k =3.64 * 10 -2 W/m K
v =30.09 * 10 -6 m2/s
P r =0.682
Β =1/160 + 273 = 2.31 * 10 -3 per K
a)
1156.5 W
b)
1146.5 W
c)
1136.5 W
d)
1126.5 W
|
|
Nandini Mishra answered |
Explanation: Q = h A d t, where h = 14.60 k/D.
Find the permeability if diffusivity is 2 units and solubility coefficient is 5 units assume all are in SI units.- a)10 units
- b)2.5 units
- c)0.4 units
- d)None of the mentioned
Correct answer is option 'A'. Can you explain this answer?
Find the permeability if diffusivity is 2 units and solubility coefficient is 5 units assume all are in SI units.
a)
10 units
b)
2.5 units
c)
0.4 units
d)
None of the mentioned
|
|
Amrutha Chatterjee answered |
Explanation: Permeability = solubility co-efficient * diffusivity
= 2 * 5 =10 units.
= 2 * 5 =10 units.
Which among the following is the statement of the ‘Fick’s Law’?- a)The molar flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species.
- b)The mass flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species.
- c)The molar flux of species relative to an observer moving with the mass average velocity is proportional to the concentration gradient of the species.
- d)The molar flux of species relative to a stationary observer is proportional to the concentration gradient of the species
Correct answer is option 'A'. Can you explain this answer?
Which among the following is the statement of the ‘Fick’s Law’?
a)
The molar flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species.
b)
The mass flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species.
c)
The molar flux of species relative to an observer moving with the mass average velocity is proportional to the concentration gradient of the species.
d)
The molar flux of species relative to a stationary observer is proportional to the concentration gradient of the species
|
|
Kiran Choudhary answered |
Explanation: None.
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