Imp Questions For All Chapters – General Science Class 8
Short Questions
1. What are the three states of matter?
- Solid, Liquid, and Gas.
2. Which state of matter has a definite shape and volume?
- Solid.
3. Which state of matter has no fixed shape but a fixed volume?
- Liquid.
4. Which state of matter is highly compressible?
- Gas.
5. What are the smallest particles of matter called?
- Atoms and molecules.
6. What is an element?
- A pure substance made of only one type of atom.
7. What is a compound?
- A substance formed when two or more elements chemically combine in a fixed ratio.
8. What is a mixture?
- A combination of two or more substances that are not chemically combined.
9. Give one example of a homogeneous mixture.
- Sugar water.
10. Give one example of a heterogeneous mixture.
- Sand and water.
11. What is a solvent?
- The substance in which a solute dissolves (e.g., water in saltwater).
12. What is a solute?
- The substance that dissolves in a solvent (e.g., salt in saltwater).
13. What is valency?
- The combining capacity of an atom.
14. What is an alloy?
- A mixture of two or more metals (e.g., brass = copper + zinc).
15. What is a nuclear reactor used for?
- To produce electricity using nuclear energy.
Long Questions
1. What are the differences between solids, liquids, and gases?
- Solids have a fixed shape and volume, liquids have a fixed volume but no fixed shape, and gases have neither a fixed shape nor volume.
2. What is the difference between a compound and a mixture?
- A compound is made of elements chemically combined in a fixed ratio, while a mixture is a physical combination of substances in any proportion.
3. Why is water a compound and not a mixture?
- Water (H₂O) has a fixed ratio of hydrogen and oxygen, and its properties are different from its elements, so it is a compound.
4. What are homogeneous and heterogeneous mixtures? Give examples.
- Homogeneous mixtures have a uniform composition (e.g., sugar water). Heterogeneous mixtures have visibly different components (e.g., sand in water).
5. What are solutions, suspensions, and colloids?
- Solutions are clear mixtures where solutes dissolve (e.g., saltwater), suspensions have particles that settle (e.g., mud in water), and colloids have particles that do not settle (e.g., milk).
6. What is the difference between an element and a compound?
- An element has only one type of atom (e.g., oxygen O₂), while a compound has two or more elements chemically combined (e.g., carbon dioxide CO₂).
7. What is the function of control rods in a nuclear reactor?
- Control rods (made of boron or cadmium) absorb extra neutrons to control the nuclear reaction and prevent explosions.
8. Why are alloys used instead of pure metals?
- Alloys have better strength, durability, and resistance to corrosion than pure metals (e.g., stainless steel is stronger than iron).
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