Very Short Question Answer: Nature of Matter: Elements, Compounds, and Mixtures | Science Curiosity Class 8 - New NCERT PDF Download

Q1: What is a homogeneous mixture of two or more substances called?
Ans: A solution is a homogeneous mixture of two or more substances.

Q2: What is an element made up of?
Ans: An element is made up of only one type of atom. For eg: Carbon (C), Iron (Fe), etc.

Q3: Name two categories of pure substances.
Ans: Element and compound.

Q4: What are two types of matter on the basis of composition?
Ans: Pure substances and mixtures are the two main types of matter based on composition.

Q5: Name the types of mixtures.
Ans: The two types of mixtures are homogeneous and heterogeneous mixtures.

Q6: Give natural examples of a mixture.
Ans: Examples of natural mixtures include seawater, mineral ores, and soil.

Q7: Name a metal that is liquid at room temperature.
Ans: Mercury is the only metal that is liquid at room temperature.

Q8: What is the principle of separation?
Ans: The principle of separation is based on differences in physical or chemical properties such as boiling point, solubility, or particle size.

Q9: Give an example of a liquid and a liquid-type solution.
Ans: Vinegar is a solution made from a mixture of acetic acid and water.

Q10: Define the term heterogeneous mixture.
Ans: A mixture where components are not uniformly distributed and properties vary is called heterogeneous.

Q11: What is a mixture, and how do its components retain their properties?
​Ans: A mixture is two or more substances mixed where each retains its individual properties, not reacting chemically.

Q12: Name two examples of uniform mixtures mentioned in the chapter.
​Ans: Sugar-water solution and air.

Q13. What happens when lime water is exposed to air, and why does it turn milky?
​Ans: Lime water turns milky due to calcium carbonate formation from reacting with carbon dioxide in air.

Q14. What are the two gases produced when electricity is passed through water, and how can they be identified?
​Ans: Hydrogen (pop sound) and oxygen (brighter flame) are produced, identified by testing with a burning candle.

Q15. Why is water considered a compound and not a mixture?
​Ans: Water is a compound because hydrogen and oxygen are chemically combined in a fixed 2:1 ratio.

Q16. What is the difference between the properties of iron sulfide (Sample B) and the mixture of iron and sulfur (Sample A)?
​Ans: Iron sulfide (Sample B) is non-magnetic and forms hydrogen sulfide with acid, unlike the magnetic, non-reacting mixture (Sample A).

Q17. Name two alloys mentioned in the chapter and their constituent elements.
​Ans: Brass (copper, zinc) and bronze (copper, tin).

Q18. What are native minerals, and give two examples of them from the chapter.
​Ans: Native minerals are pure elements; examples are gold and sulfur.

Q19. Why can’t the elements in sodium chloride be separated by physical methods?
​Ans: Sodium chloride’s elements are chemically bonded, requiring chemical methods for separation.

Q20. What is observed when sugar is heated, and what does this indicate about its composition?
​Ans: Sugar turns brown, chars to carbon, and forms water droplets, indicating it’s a compound of carbon, hydrogen, and oxygen.