Changes Around Us: Physical and Chemical Part 2: MCQs (Q26–Q50)
📘 Chapter 5 – Changes Around Us: Physical and Chemical
🔹 Part 2: Chemical Change in Daily Life (Q26–Q50)
Q26. Rusting of iron is an example of:
A) Physical change
B) Chemical change
C) Reversible change
D) None
✅ Answer: B) Chemical change
Explanation:
Rusting forms a new substance (hydrated iron oxide). It is irreversible, hence chemical.
Q27. The souring of milk is:
A) Physical change
B) Chemical change
C) Both
D) Reversible
✅ Answer: B) Chemical change
Explanation:
Souring forms lactic acid (new substance).
Q28. Which of these is NOT a chemical change?
A) Cooking food
B) Melting ice
C) Burning coal
D) Digestion of food
✅ Answer: B) Melting ice
Q29. Respiration in humans is:
A) Physical change
B) Chemical change
C) Both
D) None
✅ Answer: B) Chemical change
Explanation:
Respiration releases energy by chemical reaction of glucose and oxygen.
Q30. Photosynthesis is:
A) Physical change
B) Chemical change
C) Both
D) Reversible
✅ Answer: B) Chemical change
Q31. Burning of fuels is always a:
A) Physical change
B) Chemical change
C) Both
D) None
✅ Answer: B) Chemical change
Q32. Which of these involves a chemical reaction?
A) Boiling water
B) Baking a cake
C) Breaking glass
D) Freezing water
✅ Answer: B) Baking a cake
Explanation:
New substances form during baking (carbon dioxide, aroma compounds).
Q33. Digestion of food in our stomach is:
A) Physical change
B) Chemical change
C) Both
D) None
✅ Answer: B) Chemical change
Q34. Which of these changes involves formation of gas?
A) Rusting
B) Burning wood
C) Respiration
D) All of these
✅ Answer: D) All of these
Q35. Fermentation of sugar produces:
A) Oxygen
B) Carbon dioxide + alcohol
C) Hydrogen
D) Nitrogen
✅ Answer: B) Carbon dioxide + alcohol
Q36. Which of these is an irreversible chemical change?
A) Dissolving salt
B) Freezing water
C) Burning wood
D) Melting wax
✅ Answer: C) Burning wood
Q37. Formation of curd from milk is due to:
A) Fats
B) Bacteria
C) Minerals
D) Vitamins
✅ Answer: B) Bacteria
Explanation:
Lactobacillus bacteria convert milk into curd.
Q38. Which of the following is a desirable chemical change?
A) Rusting of iron
B) Burning of houses
C) Cooking food
D) Souring of milk
✅ Answer: C) Cooking food
Q39. Which of these is an undesirable chemical change?
A) Cooking rice
B) Ripening of fruit
C) Rusting of iron
D) Photosynthesis
✅ Answer: C) Rusting of iron
Q40. Which type of change is baking of bread?
A) Physical
B) Chemical
C) Both
D) None
✅ Answer: B) Chemical
Q41. Which change gives energy?
A) Respiration
B) Photosynthesis
C) Melting
D) Freezing
✅ Answer: A) Respiration
Explanation: Respiration releases energy, while photosynthesis stores energy.
Q42. Cooking of an egg is:
A) Physical change
B) Chemical change
C) Both
D) Reversible
✅ Answer: B) Chemical change
Q43. Burning of a candle involves:
A) Only chemical change
B) Only physical change
C) Both physical and chemical change
D) No change
✅ Answer: C) Both physical and chemical change
Explanation: Wax melts (physical), wax burns (chemical).
Q44. Formation of wine from grapes is due to:
A) Respiration
B) Fermentation
C) Photosynthesis
D) Distillation
✅ Answer: B) Fermentation
Q45. Which gas is released during respiration?
A) Oxygen
B) Carbon dioxide
C) Hydrogen
D) Nitrogen
✅ Answer: B) Carbon dioxide
Q46. Which of these changes is used in making bread fluffy?
A) Fermentation by yeast
B) Freezing water
C) Melting butter
D) Evaporation
✅ Answer: A) Fermentation by yeast
Q47. Which is a chemical change in daily life?
A) Sharpening pencil
B) Breaking chalk
C) Rusting of bicycle
D) Folding paper
✅ Answer: C) Rusting of bicycle
Q48. Which change occurs when vinegar is added to baking soda?
A) Only physical change
B) Only chemical change
C) Both physical and chemical change
D) No change
✅ Answer: B) Only chemical change
Explanation: Reaction forms carbon dioxide + new substances.
Q49. Which process in plants is a chemical change?
A) Transpiration
B) Photosynthesis
C) Absorption of water
D) Movement of roots
✅ Answer: B) Photosynthesis
Q50. Respiration is opposite to:
A) Fermentation
B) Photosynthesis
C) Burning
D) Evaporation
✅ Answer: B) Photosynthesis
Explanation:
- Photosynthesis stores energy in glucose.
- Respiration releases energy by breaking glucose.
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