👉 ALL NMMS INTERACTIVE TESTS 👈
NMMS CLASS 7 Physical and Chemical Changes 4👇
1. The color of copper vessels turns green after some time because
- Copper reacts with moist carbon dioxide forming basic copper carbonate
- Copper absorbs water
- Copper dissolves in air
- Dust deposits on copper
Correct Answer: Copper reacts with moist carbon dioxide forming basic copper carbonate
2. When baking soda is mixed with lemon juice, bubbles are formed due to
- Carbon dioxide gas
- Hydrogen gas
- Oxygen gas
- Nitrogen gas
Correct Answer: Carbon dioxide gas
3. A blacksmith heats an iron piece before hammering because
- Heating makes it soft and easy to shape
- It increases its weight
- It reduces its density
- It reacts with oxygen
Correct Answer: Heating makes it soft and easy to shape
4. When ice is converted into water, what type of change occurs?
- Chemical change
- Temporary change
- Physical change
- Irreversible change
Correct Answer: Physical change
5. Burning of magnesium ribbon produces a dazzling white light and white ash. The ash is
- Magnesium oxide
- Magnesium chloride
- Magnesium hydroxide
- Calcium oxide
Correct Answer: Magnesium oxide
6. When silver articles turn black, the black layer formed is
- Silver sulphide
- Silver oxide
- Silver carbonate
- Silver chloride
Correct Answer: Silver sulphide
7. In which of the following changes energy is released?
- Burning of fuel
- Melting of ice
- Evaporation of water
- Boiling of water
Correct Answer: Burning of fuel
8. When water changes into vapour, it is
- Chemical change
- Temporary change
- Physical change
- Reversible change
Correct Answer: Physical change
9. When milk is converted into curd, it is a
- Physical change
- Reversible change
- Chemical change
- Temporary change
Correct Answer: Chemical change
10. When butter melts in a hot pan, the process is
- Chemical change
- Temporary change
- Physical change
- Irreversible change
Correct Answer: Physical change
11. When an iron nail is kept in copper sulphate solution, the brown coating formed is due to
- Deposition of copper on iron
- Formation of rust
- Oxidation of iron
- Corrosion by water
Correct Answer: Deposition of copper on iron
12. When a candle burns, the melting of wax is
- Chemical change
- Reversible change
- Physical change
- Permanent change
Correct Answer: Physical change
13. Burning of a candle wax is
- Physical change
- Reversible change
- Chemical change
- Temporary change
Correct Answer: Chemical change
14. Cooking food involves
- Physical change
- Temporary change
- Chemical change
- Reversible change
Correct Answer: Chemical change
15. When water vapour changes into liquid, the process is
- Evaporation
- Sublimation
- Condensation
- Melting
Correct Answer: Condensation
16. When ammonium chloride is heated, it disappears and forms vapours. The process is
- Evaporation
- Boiling
- Sublimation
- Combustion
Correct Answer: Sublimation
17. Rusting of iron requires
- Only air
- Only moisture
- Both air and moisture
- Light
Correct Answer: Both air and moisture
18. The color change during rusting is due to
- Formation of hydrated iron oxide
- Evaporation of water
- Deposition of dust
- Physical change
Correct Answer: Formation of hydrated iron oxide
19. When sugar solution is heated strongly, it becomes brown. This indicates
- Physical change
- Temporary change
- Chemical change
- Reversible change
Correct Answer: Chemical change
20. The reaction between an acid and a metal gives
- Hydrogen gas
- Carbon dioxide
- Oxygen
- Nitrogen
Correct Answer: Hydrogen gas
21. The chemical formula of rust is
- Fe₂O₃·xH₂O
- FeO
- FeCO₃
- FeCl₂
Correct Answer: Fe₂O₃·xH₂O
22. Which one is a fast chemical change?
- Rusting of iron
- Tarnishing of silver
- Souring of milk
- Explosion of fireworks
Correct Answer: Explosion of fireworks
23. Which one is a slow chemical change?
- Burning of paper
- Explosion of crackers
- Melting of ice
- Fermentation of grapes
Correct Answer: Fermentation of grapes
24. When ice melts, the change in temperature causes
- Chemical change
- Reversible change
- Physical change
- Permanent change
Correct Answer: Physical change
25. Which one among the following is an exothermic reaction?
- Melting of ice
- Evaporation of water
- Dissolution of salt
- Burning of wood
Correct Answer: Burning of wood
26. Which change occurs when food is digested?
- Physical change
- Temporary change
- Chemical change
- Reversible change
Correct Answer: Chemical change
27. Why is rusting considered a harmful chemical change?
- It weakens the metal
- It strengthens metal
- It makes metal shiny
- It increases weight only
Correct Answer: It weakens the metal
28. Which change can be reversed easily?
- Cooking of rice
- Burning of paper
- Rusting of iron
- Freezing of water
Correct Answer: Freezing of water
29. Formation of clouds from water vapour is
- Chemical change
- Irreversible change
- Physical change
- Permanent change
Correct Answer: Physical change
30. Burning of fuel is
- Physical change
- Reversible change
- Chemical change
- Temporary change
Correct Answer: Chemical change
31. Which of the following processes involves both change of state and energy?
- Melting
- Evaporation
- Evaporation
- Rusting
Correct Answer: Condensation
32. Why does iron rust more quickly near the sea?
- Salt and moisture in air speed up rusting
- Sunlight increases oxidation
- Air pressure is high
- Temperature is low
Correct Answer: Salt and moisture in air speed up rusting
33. Which one of the following is a reversible change?
- Cooking food
- Burning wood
- Souring milk
- Melting of ice cream
Correct Answer: Melting of ice cream
34. Which change shows production of a new substance and heat?
- Melting
- Condensation
- Combustion
- Sublimation
Correct Answer: Combustion
35. Which change involves oxidation?
- Melting of wax
- Freezing of water
- Cutting paper
- Rusting of iron
Correct Answer: Rusting of iron
36. Cutting of vegetables is a
- Chemical change
- Temporary change
- Physical change
- Permanent change
Correct Answer: Physical change
37. Heating of iron and sulphur produces
- Iron sulphide
- Iron oxide
- Iron chloride
- Iron carbonate
Correct Answer: Iron sulphide
38. When sugar dissolves in water, it can be recovered by
- Condensation
- Filtration
- Evaporation
- Sublimation
Correct Answer: Evaporation
39. Mixing sand and salt is a
- Chemical change
- Irreversible change
- Physical change
- Temporary change
Correct Answer: Physical change
40. The change that cannot be reversed is
- Melting of ice
- Condensation of vapour
- Burning of paper
- Freezing of water
Correct Answer: Burning of paper
41. Heating of limestone gives
- Quicklime
- Slaked lime
- Limestone
- Chalk powder
Correct Answer: Quicklime
42. The change of water into ice involves
- Gain of heat
- No heat exchange
- Loss of heat
- Absorption of oxygen
Correct Answer: Loss of heat
43. Which of the following is not a sign of chemical change?
- Change in colour
- Evolution of gas
- Release of heat
- Change in state
Correct Answer: Change in state
44. When vinegar reacts with baking soda, it is
- Physical change
- Temporary change
- Chemical change
- Reversible change
Correct Answer: Chemical change
45. The rusting of iron is prevented by
- Heating in air
- Immersing in acid
- Painting and galvanising
- Scratching the surface
Correct Answer: Painting and galvanising
46. Cooking of egg is a
- Physical change
- Temporary change
- Chemical change
- Reversible change
Correct Answer: Chemical change
47. Melting of wax is
- Chemical change
- Temporary change
- Physical change
- Permanent change
Correct Answer: Physical change
48. Which one of the following is a permanent change?
- Melting of butter
- Freezing of water
- Boiling of water
- Souring of milk
Correct Answer: Souring of milk
49. When a piece of paper is burnt,
- Carbon dioxide and ash are formed
- No new substance forms
- Water vapour forms only
- Smoke deposits only
Correct Answer: Carbon dioxide and ash are formed
50. The most suitable method to prevent rusting is
- Coating with zinc
- Dipping in water
- Exposing to air
- Polishing with sand
Correct Answer: Coating with zinc
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