1. When magnesium ribbon burns in air, a white ash is formed. This shows
- A new substance is formed — chemical change
- No new substance formed — physical change
- State change only
- Temporary change
Correct Answer: A new substance is formed — chemical change
2. When water is cooled below 0°C, it becomes ice. This shows
- New substance formed
- Irreversible chemical change
- Change in state — physical change
- Heat release only
Correct Answer: Change in state — physical change
3. A student mixes iron filings and sulphur powder. Which observation shows a chemical change has occurred?
- No color change
- Powder remains yellow
- Magnetic property unchanged
- Formation of black iron sulphide on heating
Correct Answer: Formation of black iron sulphide on heating
4. A piece of paper is burnt in air. Which evidence confirms a chemical change?
- Change in size
- No color change
- Formation of ash and smoke
- Temporary melting
Correct Answer: Formation of ash and smoke
5. Ice melts to form water and again freezes on cooling. This indicates
- Irreversible chemical change
- Reversible physical change
- New substance formation
- Gas evolution
Correct Answer: Reversible physical change
6. When vinegar reacts with baking soda, bubbles form. The gas evolved is
- Oxygen
- Hydrogen
- Nitrogen
- Carbon dioxide
Correct Answer: Carbon dioxide
7. A student heats sugar in a spoon and it turns brown. This indicates
- New substance formed — chemical change
- Physical change
- Temporary change
- Evaporation only
Correct Answer: New substance formed — chemical change
8. When iron nails are kept in moist air for a few days, they turn reddish-brown. This happens due to
- Evaporation
- Physical polishing
- Reversible change
- Rusting — chemical change
Correct Answer: Rusting — chemical change
9. A copper coin left in air becomes green. This green coating is due to
- Basic copper carbonate — chemical change
- Copper sulphate
- Dust accumulation
- Copper oxide only
Correct Answer: Basic copper carbonate — chemical change
10. When wax melts and burns simultaneously in a candle, what kind of changes occur?
- Both physical and chemical changes
- Only physical change
- Only chemical change
- Reversible change
Correct Answer: Both physical and chemical changes
11. When camphor disappears from a plate kept open, it undergoes
- Evaporation — chemical change
- Sublimation — physical change
- Burning
- Melting
Correct Answer: Sublimation — physical change
12. The solution of lead nitrate when mixed with potassium iodide produces a yellow solid. This yellow solid is
- Lead iodide — chemical change
- Sulphur
- Sodium chloride
- Copper oxide
Correct Answer: Lead iodide — chemical change
13. A blacksmith heats iron before shaping it. This is a
- Chemical change
- Irreversible change
- Reaction with oxygen
- Physical change
Correct Answer: Physical change
14. When limestone is heated strongly, a new white solid is formed with gas evolution. The white solid is
- Quicklime — chemical change
- Calcium carbonate
- Chalk powder
- Slaked lime
Correct Answer: Quicklime — chemical change
15. When sodium reacts with water, bubbles appear and heat is released. This is
- Physical change
- Temporary change
- Exothermic chemical change
- Reversible change
Correct Answer: Exothermic chemical change
16. When a student mixes sand and salt, he can separate them by
- Filtration and evaporation — physical process
- Heating
- Chemical reaction
- Rusting
Correct Answer: Filtration and evaporation — physical process
17. On adding zinc granules to dilute hydrochloric acid, bubbles appear. The gas evolved is
- Hydrogen — chemical change
- Oxygen
- Carbon dioxide
- Nitrogen
Correct Answer: Hydrogen — chemical change
18. A student boils water and observes steam. This process involves
- Change in state — physical change
- New substance formation
- Color change
- Irreversible reaction
Correct Answer: Change in state — physical change
19. The rust formed on iron is
- Iron carbonate
- Iron sulphide
- Ferric chloride
- Hydrated iron oxide
Correct Answer: Hydrated iron oxide
20. When bleaching powder is added to water, chlorine gas smell appears. This indicates
- Chemical change
- Physical change
- Temporary change
- Evaporation
Correct Answer: Chemical change
21. When silver nitrate solution is added to salt solution, a white curdy precipitate appears. It is
- Silver chloride
- Calcium carbonate
- Zinc sulphate
- Iron oxide
Correct Answer: Silver chloride
22. Burning of LPG (liquefied petroleum gas) in the kitchen is
- Physical change
- Reversible change
- Temporary change
- Chemical change
Correct Answer: Chemical change
23. When molten wax cools down to become solid, it is a
- Physical change
- Chemical change
- Irreversible change
- Permanent change
Correct Answer: Physical change
24. When a student shakes sugar and sand together, the mixture can be separated by
- Sieving — physical method
- Evaporation
- Chemical change
- Dissolution
Correct Answer: Sieving — physical method
25. When baking soda is heated, it gives carbon dioxide gas and water vapour. This is
- Physical change
- Chemical change
- Temporary change
- Condensation
Correct Answer: Chemical change
26. A colorless solution of copper sulphate turns blue when hydrated. This shows
- Physical change — addition of water
- Chemical change
- Evaporation
- Corrosion
Correct Answer: Physical change — addition of water
27. When water vapour cools on the mirror surface, tiny droplets form. This process is
- Condensation — physical change
- Evaporation
- Sublimation
- Corrosion
Correct Answer: Condensation — physical change
28. A brown gas is released on heating lead nitrate crystals. This is
- Nitrogen dioxide — chemical change
- Hydrogen sulphide
- Sulphur dioxide
- Carbon monoxide
Correct Answer: Nitrogen dioxide — chemical change
29. When curd is added to milk and left overnight, milk turns to curd due to
- Bacterial action — chemical change
- Evaporation
- Reversible reaction
- Freezing
Correct Answer: Bacterial action — chemical change
30. When paper burns, energy is released as
- Heat and light — chemical change
- Only heat
- Only light
- No energy
Correct Answer: Heat and light — chemical change
31. When we inflate a balloon, it is
- Chemical change
- Irreversible
- Permanent change
- Physical change
Correct Answer: Physical change
32. When coal is burnt in air, which gases are produced?
- Oxygen and nitrogen
- Methane and hydrogen
- Carbon monoxide only
- Carbon dioxide and water vapour
Correct Answer: Carbon dioxide and water vapour
33. A student heats copper wire in a flame; it turns black. This happens because
- Copper forms copper oxide — chemical change
- It melts
- It polishes itself
- It reflects heat
Correct Answer: Copper forms copper oxide — chemical change
34. When iodine crystals are heated, violet vapours are seen. This process is
- Sublimation — physical change
- Evaporation
- Combustion
- Oxidation
Correct Answer: Sublimation — physical change
35. When iron is galvanised, it is coated with
- Copper
- Zinc
- Silver
- Carbon
Correct Answer: Zinc
36. A student burns magnesium ribbon; after cooling, white powder remains. This powder is
- Magnesium chloride
- Magnesium oxide
- Magnesium sulphate
- Calcium oxide
Correct Answer: Magnesium oxide
37. When fruit juice is left open for days, it ferments. This is
- Chemical change
- Physical change
- Temporary change
- Freezing
Correct Answer: Chemical change
38. The rusting of iron is faster in rainy season because
- Presence of moisture and oxygen
- Presence of nitrogen
- High sunlight
- Dry air
Correct Answer: Presence of moisture and oxygen
39. When camphor disappears from a plate kept in open air, it is due to
- Sublimation — physical change
- Evaporation — chemical
- Rusting
- Melting
Correct Answer: Sublimation — physical change
40. A student observes bubbles on mixing acid and marble chips. The gas released is
- Hydrogen
- Oxygen
- Methane
- Carbon dioxide
Correct Answer: Carbon dioxide
41. When food gets spoiled, bad smell appears. It indicates
- Chemical change
- Physical change
- Evaporation
- Dissolution
Correct Answer: Chemical change
42. The burning of firewood produces charcoal, ash, and gases. This is
- Chemical change
- Physical change
- Reversible
- Temporary change
Correct Answer: Chemical change
43. Condensation on a cold glass surface shows
- Change of state — physical change
- Formation of new substance
- Chemical reaction
- Evaporation
Correct Answer: Change of state — physical change
44. When a piece of chalk is dipped in vinegar, bubbles form. This is due to
- Formation of carbon dioxide
- Evaporation of vinegar
- Absorption of gas
- Change in shape
Correct Answer: Formation of carbon dioxide
45. When you burn camphor, it gives smoke and smell. This shows
- Physical change
- Temporary change
- Chemical change
- Condensation
Correct Answer: Chemical change
46. When perfume spreads in a room, it is due to
- Diffusion — physical change
- Evaporation — chemical change
- Reaction with air
- Combustion
Correct Answer: Diffusion — physical change
47. The black coating on iron utensils used for long time is
- Rust — chemical change
- Dust layer
- Wax coating
- Soot deposit
Correct Answer: Rust — chemical change
48. When lime water is exposed to air, it turns milky due to
- Carbon dioxide forming calcium carbonate
- Absorption of oxygen
- Evaporation
- Condensation
Correct Answer: Carbon dioxide forming calcium carbonate
49. When we cook vegetables, they change color and smell. This indicates
- Physical change
- Temporary change
- Condensation
- Chemical change
Correct Answer: Chemical change
50. When solid iodine forms violet vapours and later reappears as solid, the change is
- Sublimation — reversible physical change
- Chemical reaction
- Corrosion
- Irreversible change
Correct Answer: Sublimation — reversible physical change
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