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All questions of Class 7 for BPSC (Bihar) Exam

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Which one of the following is not an example of natural fibre?
  • a)
    Rayon
  • b)
    Cotton
  • c)
    Wool
  • d)
    Silk
Correct answer is option 'A'. Can you explain this answer?

Rithika Roy answered
Silk, cotton and wood are obtained from natural sources either plant or animal but rayon is a synthetic fibre.

Q.Silkworms feeds on leaves of
a)Guava
b)Mulberry
c)Banana
d)Mango
Correct answer is option 'B'. Can you explain this answer?

Kavya Rane answered
Silkworms can ONLY survive on mulberry leaves (genus Morus), sometimes Osage orange (Maclura pomifera) or silkworm food, which is made from mulberry leaves. Your worms may eat other types of vegetation, such as lettuce leaves, but it will kill them.

Acid turns blue litmus
A: Orange
B: Pink
C: green
D: Red
Correct answer is 'D'. Can you explain this answer?

Jithin Chawla answered
Acids turn blue litmus red. Litmus paper is used as indicator to check acids and bases.

Select the correct match
  • a)
    Natural fibre – cotton
  • b)
    Synthetic fibre – silk
  • c)
    Animal fibre – jute
  • d)
    Plant fibre – wool
Correct answer is option 'A'. Can you explain this answer?

Vikram Kapoor answered
  • Cotton is a natural fibre.
  • Wool is not a plant fibre. 
  • Jute is a plant fibre.
  • Silk is a fibre obtained from cocoons of insects and is a natural fibre.

During exhalation, the ribs move
  • a)
    Outwards
  • b)
    Downwards
  • c)
    Upwards
  • d)
    To normal position
Correct answer is option 'B'. Can you explain this answer?

Disha Iyer answered
During exhalation, i.e. releasing air during respiration, the ribs move downwards to reduce the volume of the thoracic cavity.
During exhalation, your diaphragm relaxes and moves upward into the chest cavity. The intercostal muscles between the ribs also relax to reduce the space in the chest cavity. As they relax they position the rib cage downwards and inwards.

Which of the following is a natural indicator
  • a)
    Turmeric
  • b)
    Methyl orange
  • c)
    Oxalic acid.
  • d)
    Phenolphthalein
Correct answer is option 'A'. Can you explain this answer?

Sanjana Kumar answered
Some of the natural indicators are red cabbage juice, onion paste, turmeric, lemon juice etc. Natural indicators are turmric,litmus,china rose etc are some natural indicators. Some Natural Indicators are red Cabbage juice,turmeric,china rose[hibiscus] and litmus.

First man-made synthetic fibre is
a)Cotton
b)Nylon
c)Rayon
d)Polyester
Correct answer is option 'B'. Can you explain this answer?

Vibhor Goyal answered
  • Rayon is an artificial fibre, but not truly synthetic, being made from wood.
  • Nylon, the first synthetic fibre in the "fully synthetic" sense of that term, was developed by Wallace Carothers, an American researcher at the chemical firm DuPont in the 1930s.

Practice Quiz or MCQ (Multiple Choice Questions) with solutions are available for Practice, which would help you prepare for chapter  Physical and Chemical Changes, Class 7, Science. You can practice these practice quizzes as per your speed and improvise the topic. 
Q.
Melting of ice is a
  • a)
    Both physical and chemical change
  • b)
    Chemical change
  • c)
    Periodic change
  • d)
    Physical change
Correct answer is 'D'. Can you explain this answer?

Maitri Sarkar answered
Melting of ice is a physical change because it involves change only in the physical state of water: from ice in the solid state to water in the liquid state. 
Moreover, no new chemical substance is formed in the process and this change is reversible. Water can be converted back into ice simply by freezing.

Silk thread is obtained from
  • a)
    Cocoon
  • b)
    Caterpillar
  • c)
    Pupa
  • d)
    Adult moth
Correct answer is option 'A'. Can you explain this answer?

Meera Reddy answered
The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture).

A device which prevents or allow the current to flow through it
  • a)
    Motor
  • b)
    Terminal
  • c)
    Conductor
  • d)
    Switch
Correct answer is option 'D'. Can you explain this answer?

Rohini Seth answered
A circuit breaker can be used over and over again. The basic circuit breaker consists of a simple switch, connected to an electromagnet.
Generally electrical current requires a close path or circuit to flow, so when switch is off it won't flow. A switch prevents or allow the current to flow through it.

In insects, air enters the body through
  • a)
    Spiracles
  • b)
    Gills
  • c)
    Lungs
  • d)
    Skin
Correct answer is option 'A'. Can you explain this answer?

Maitri Sarkar answered
Insect bodies have openings, called spiracles, along the thorax and abdomen. These openings connect to the tubular network, allowing oxygen to pass into the body, regulating the diffusion of CO2 and water vapor. 

Which of the following fibre is not obtained from animals?
  • a)
    Leather
  • b)
    Wool
  • c)
    Silk cotton
  • d)
    Silk
Correct answer is 'C'. Can you explain this answer?

Kajal Shah answered
Silk cotton is a plant fiber from the KAPOK tree used for stuffing for pillows and lifejackets and insulation. Silk cotton is a big tree of 6070 feet tall and 1540 feet wide. It has a soft wood, red flowers, large number of seeds and smaller filaments, Its’s cotton i.e. Silk cotton is softer than the regular cotton.

The excess of water absorbed plants by their roots gets evaporated through the process of
  • a)
    Absorption
  • b)
    Elimination
  • c)
    Transpiration
  • d)
    Excretion
Correct answer is option 'C'. Can you explain this answer?

Prisha Mehta answered
Plants lose gallons of water every day through the process of transpiration, the evaporation of water from plants primarily through pores in their leaves. Up to 99% of the water absorbed by roots is lost via transpiration through plant leaves.

Which of the following is a reversible change?
  • a)
    Melting of ice
  • b)
    Germination of seed
  • c)
    Burning of matchstick
  • d)
    Changing of milk into curd
Correct answer is option 'A'. Can you explain this answer?

Varun Kapoor answered
Melting of ice is a reversible change while burning of matchstick, changing of milk into curd and germination of seed is chemical change.

What is the name of object through which light can pass?
  • a)
    Opaque
  • b)
    Translucent
  • c)
    Transparent
  • d)
    Luminous
Correct answer is option 'C'. Can you explain this answer?

Sanaya Shah answered
The object through which light can pass easily is called transparent object. Glass, water and thin plastic sheets are transparent object.

Water is a/an
  • a)
    Element
  • b)
    Mixture
  • c)
    Solution
  • d)
    Compound
Correct answer is option 'D'. Can you explain this answer?

Anand Iyer answered
Water is a compound as it contains hydrogen and oxygen in fixed ration by mass.

Rainwater harvesting is a method of
  • a)
    Water Conversation
  • b)
    Producing water for future use
  • c)
    Using rain water for daily purpose
  • d)
    All of these
Correct answer is option 'A'. Can you explain this answer?

Pragati Choudhary answered
Rain water harvesting is a method of water conservation by collection of rainwater mostly from the roof into a tank. It can then be used for multiple purposes. If untreated it can be used for watering the plants, washing the livestock etc. If treated properly it can be used for domestic purposes and even for drinking. One important application of collected rain water is to recharge the ground water.

There is acute water shortage due to
  • a)
    Excessive population growth
  • b)
    Climate change
  • c)
    Global warming
  • d)
    Excess evaporation
Correct answer is option 'A'. Can you explain this answer?

Advait Pillai answered
There is acute shortage of water throughout the world due to excessive population growth which leads to overuse and misuse of water.

Climate of a place do not depends on
  • a)
    Latitude
  • b)
    Wind
  • c)
    Humidity
  • d)
    Longitude
Correct answer is option 'D'. Can you explain this answer?

Palak Iyer answered
The factors that determine the climate of a place are:
· Latitude
· Altitude
· Winds
· Distance from the sea
· Humidity and Ocean Currents
Longitude is not a factor that determines the climate of a place.

Practice Quiz or MCQ (Multiple Choice Questions) with solutions are available for Practice, which would help you prepare for chapter Water A Precious Resource, Class 7, Science. You can practice these practice quizzes as per your speed and improvise the topic. 
Q.
Ground water between two layers of rocks is called
  • a)
    Rain water
  • b)
    Water table
  • c)
    Aquifer
  • d)
    Water level
Correct answer is 'C'. Can you explain this answer?

Kiran Bajaj answered
If groundwater is between two confined layers, it is called confined aquifer. If groundwater is not confined by an upper confining layer, it is unconfined equifer. If, on the other hand, groundwater is confined by two confining units (such as upper confining layer and lower confining layer), it is called confined aquifer.

Silk fibre is drawn from ____________ of silk moth.
  • a)
    Hair
  • b)
    Caterpillar
  • c)
    Pupa
  • d)
    Cocoon
Correct answer is option 'D'. Can you explain this answer?

Kiran Mehta answered
Following are the stages of production of silk:

1. The silk moth lays thousands of eggs.
2. The silk moth eggs hatch to form larvae or caterpillars, known as silkworms.
3. The larvae feed on mulberry leaves.
4. Having grown and moulted several times, the silkworm extrudes a silk fiber and forms a net to hold itself.
5. It swings itself from side to side in a figure '8' distributing the saliva that will form silk.
6. The silk solidifies when it contacts the air.
7. The silkworm spins approximately one mile of filament and completely encloses itself in a cocoon in about two or three days. The amount of usable quality silk in each cocoon is small. As a result, about 2500 silkworms are required to produce a pound of raw silk.
8. The intact cocoons are boiled, killing the silkworm pupa.
9. The silk is obtained by brushing the undamaged cocoon to find the outside end of the filament.
10. The silk filaments sec then wound on a reel. One cocoon contains approximately 1,000 yards of silk filament. The silk at this stage is known as raw silk. One thread comprises up to 48 individual silk filaments.

Q. The centre of cyclone is known as
a)Eyes of hurricanes
b)Ear of hurricanes
c)Middle of hurricanes
d)Nose of hurricanes
Correct answer is option 'A'. Can you explain this answer?

Prashanth Sen answered
The most recognizable feature found within a cyclone is the eye. They are found at the center and are between 20-50km in diameter. The eye is the focus of the cyclone, the point about which the rest of the storm rotates and where the lowest surface pressures are found in the storm

Practice Quiz or MCQ (Multiple Choice Questions) with solutions are available for Practice, which would help you prepare for chapter Waste water Story, Class 7, Science. You can practice these practice quizzes as per your speed and improvise the topic. 
Q.
Liquid waste from houses is called
  • a)
    Sludge
  • b)
    Effluent
  • c)
    Smog
  • d)
    Sewage
Correct answer is option 'D'. Can you explain this answer?

Anita Menon answered
Sewage is wastewater released by homes, industries, hospitals, offices and other users. It also includes rainwater that has run down the street during a storm or heavy rain. The water that washes off roads and rooftops carries harmful substances with it. Sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities.

Chemical changes are
  • a)
    Always irreversible
  • b)
    Mostly reversible
  • c)
    Always reversible
  • d)
    Mostly irreversible
Correct answer is option 'A'. Can you explain this answer?

Lakshmi Reddy answered
Crystals of copper sulphate are prepared by the method of crystallization. It is an example of physical change.
So option D is correct answer. 

Birds are adapted to fly because of 
  • a)
    Streamlined body
  • b)
    light bones 
  • c)
    feathers and wings 
  • d)
    all of these 
Correct answer is option 'D'. Can you explain this answer?

Mayank Roy answered
The bodies of birds are adapted for flying. Many of a bird's bones are hollow which makes birds' bodies lightweight. Flying birds have large chest muscles that move the wings.The long flight feathers on the wings and tail help birds balance and steer.

During flood drinking water should be
  • a)
    Sedimented
  • b)
    Filtered
  • c)
    All of these
  • d)
    Boiled
Correct answer is option 'C'. Can you explain this answer?

Keerthana Basak answered
During a flood, it is important to ensure that drinking water is safe for consumption. Here are the steps to make sure the water is safe:

- Sedimented: Allow the water to sit undisturbed so that sediment and particles can settle at the bottom.
- Filtered: Use a filtering system or boil water and then filter it to remove any remaining impurities.
- Boiled: Boil the water for at least one minute to kill any harmful bacteria or pathogens present.

By following these steps, you can ensure that the drinking water is safe to consume during a flood.

The process of removal of fleece from the body of sheep is called
  • a)
    Cleaning
  • b)
    Carding
  • c)
    Shearing
  • d)
    Removal
Correct answer is 'C'. Can you explain this answer?

Vandana Mukherjee answered
Sheep shearing is the process by which the woollen fleece of a sheep is cut off. The person who removes the sheep's wool is called a shearer. Typically each adult sheep is shorn/sheared once each year.
The annual shearing most often occurs in a shearing shed, a facility especially designed to process often hundreds and sometimes more than 3,001 sheep per day.

Sheep are shorn in all seasons, depending on the climate, management requirements and the availability of a woolclasser and shearers.

Which of the following is a reversible change?
  • a)
    Melting of ice
  • b)
    Germination of seed
  • c)
    Changing of milk into curd
  • d)
    Burning of match stick
Correct answer is option 'A'. Can you explain this answer?

Meera Reddy answered
If we take certain amount of ice and we start it heating we will slowly begin to observe that the ice is melting and it is turning to water.
This process is called melting and it is reversible.This is because when ice has turned to water after heating,when we place the same melted water and begin to freeze it,we will find that it is slowly being converted into ice.Hence,proving that melting of ice is a reversible process!

In irrigation, which technique reduces the water loss?
  • a)
    Tube well system
  • b)
    Planting crops in rainy season
  • c)
    Canal system
  • d)
    Drip irrigation
Correct answer is option 'D'. Can you explain this answer?

Vandana Mukherjee answered
Drip and sprinkler irrigation systems are the most water efficient irrigation systems. They deliver water directly to a plant's roots, reducing the evaporation that happens with spray watering systems. Timers can be used to schedule watering during the cooler parts of the day which further reduces water loss.

The speed of the vehicle is recorded by
  • a)
    Ammeter
  • b)
    Odometer
  • c)
    Speedometer
  • d)
    Voltmeter
Correct answer is option 'C'. Can you explain this answer?

Jyoti Kulkarni answered
 
  • The speedometer is a device found in vehicles that measures the current speed of the vehicle.
  • It provides real-time information, allowing drivers to maintain safe speeds and abide by traffic regulations.
  • Unlike an odometer, which measures distance traveled, the speedometer focuses solely on speed.
  • Ammeter and voltmeter measure electrical current and voltage, respectively, and are not related to vehicle speed.
 
Topic in NCERT: Measuring Speed
Line in NCERT: "The speedometer records the speed directly in km/h."

What will happen if carbon dioxide gas is passed through lime water?
  • a)
    Calcium carbonate is formed
  • b)
    The lime water turns milky
  • c)
    Both of these
  • d)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Bespoke Classes answered
Explanation:


  • Formation of Calcium Carbonate: When carbon dioxide gas is passed through lime water, a chemical reaction occurs where the carbon dioxide reacts with the calcium hydroxide in the lime water to form calcium carbonate.

  • Lime Water Turns Milky: The formation of calcium carbonate results in the lime water turning milky or cloudy in appearance.

  • Both of These: Therefore, when carbon dioxide gas is passed through lime water, both the formation of calcium carbonate and the milky appearance of the lime water are observed as a result of the chemical reaction.

Which one is not an adaptation of camel for desert condition
  • a)
    It excrete very little of urine and dry dung.
  • b)
    Its feet are broad with paddy soles
  • c)
    It has hump which stores fat
  • d)
    It perspires a lot to keep the body cool
Correct answer is option 'D'. Can you explain this answer?

Akshara Das answered
Camels have many adaptations that allow them to live successfully in desert conditions. Deserts are hot and dry. Winds blow sand all around, so a camel has long eyelashes. It has nostrils that can open and close.

1. A camel can go a week or more without water, and they can last for several months without food. They can drink up to 32 gallons (46 litres) of water at one drinking session! 
2. Camels store fat in the hump, not water. The fat can be metabolised for energy.
3. Unlike most mammals, a healthy camel's body temperature fluctuates (changes) throughout the day from 34degC to 41.7degC (93degF-107degF.) This allows the camel to conserve water by not sweating as the environmental temperature rises.
4. Camels feet are wide so they can walk on sand more easily. Their huge feet help them to walk on sand without sinking into it.
5. Camels have thick lips so they can eat the prickly desert plants with out feeling pain.
6. The colour of their bodies helps them to blend into their environment.
7. Camel's ears are covered with hair, even on the inside. The hair helps keep out sand or dust that might blow into the animal's ears.

In human eyes, image is formed on
  • a)
    Eye lens
  • b)
    Cornea
  • c)
    Retina
  • d)
    Pupil
Correct answer is option 'C'. Can you explain this answer?

Bhaskar Desai answered
Formation of Image in Human Eye

The human eye is a complex organ that is responsible for vision. It captures the light that enters the eye and converts it into electrical impulses that are sent to the brain for interpretation. The image formation in the human eye involves the following steps:

1. Cornea:
The cornea is the transparent outer layer of the eye that covers the iris, pupil, and anterior chamber. It acts as a protective barrier and helps to refract (bend) light as it enters the eye.

2. Pupil:
The pupil is the black circular opening in the center of the iris. It controls the amount of light that enters the eye by dilating (opening up) or constricting (closing down) in response to changes in light intensity.

3. Lens:
The lens is a transparent, biconvex structure located behind the iris. It helps to focus light onto the retina by changing its shape. The process of changing the shape of the lens is called accommodation.

4. Retina:
The retina is the innermost layer of the eye that contains photoreceptor cells called rods and cones. These cells convert light into electrical impulses that are sent to the brain via the optic nerve for interpretation.

5. Optic Nerve:
The optic nerve is a bundle of nerve fibers that carries the electrical impulses from the retina to the brain.

6. Brain:
The brain receives the electrical impulses from the optic nerve and interprets them as images.

Conclusion:
Thus, the image is formed on the retina of the human eye. The cornea and lens work together to focus the light onto the retina, which contains the photoreceptor cells that convert the light into electrical impulses that are sent to the brain for interpretation.

Clay particles are of size
  • a)
    More than 0.004 mm
  • b)
    Less than 0.04 mm
  • c)
    More than 0.02 mm
  • d)
    Less than 0.002 mm
Correct answer is option 'D'. Can you explain this answer?

Bibek Singh answered
The soils that contain particles of size less than 0.002mm are called clayey soil. It is most suitable for rice, wheat and gram.

Chapter doubts & questions for Class 7 - Science & Technology for State PSC Exams 2025 is part of BPSC (Bihar) exam preparation. The chapters have been prepared according to the BPSC (Bihar) exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for BPSC (Bihar) 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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