Last updated on December 9th, 2023 at 09:06 pm
Class 7 Science Physical and Chemical Changes
Test your knowledge of Physical and Chemical Changes in Class 7 Science with our engaging multiple-choice questions (MCQs).
Que: Which of the following is an example of a physical change?
a) Rusting of iron
b) Burning of wood
c) Melting of ice
d) Cooking an egg
Answer: c) Melting of ice
Que: Which of the following is an example of a chemical change?
a) Boiling of water
b) Dissolving sugar in water
c) Freezing of liquid nitrogen
d) Rusting of iron
Answer: d) Rusting of iron
Que: What is rust?
a) A gaseous substance
b) A liquid substance
c) A solid substance
d) A mixture of substances
Answer: c) A solid substance
Que: What causes rusting of iron?
a) Exposure to heat
b) Reaction with oxygen and moisture
c) Contact with acids
d) Mixing with other metals
Answer: b) Reaction with oxygen and moisture
Que: What is the result of rusting on iron objects?
a) Formation of a protective layer
b) Enhancement of durability
c) Prevention of further damage
d) Damage and deterioration over time
Answer: d) Damage and deterioration over time
Que: What is formed when a small piece of magnesium strip burns in a candle flame?
a) Magnesium hydroxide
b) Magnesium oxide
c) Magnesium chloride
d) Magnesium sulfate
Answer: b) Magnesium oxide
Que: How can the chemical change of magnesium burning be represented?
a) Magnesium (Mg) + Oxygen (O2) → Magnesium oxide (MgO)
b) Magnesium (Mg) + Carbon dioxide (CO2) → Magnesium oxide (MgO)
c) Magnesium (Mg) + Hydrogen (H2) → Magnesium oxide (MgO)
d) Magnesium (Mg) + Nitrogen (N2) → Magnesium oxide (MgO)
Answer: a) Magnesium (Mg) + Oxygen (O2) → Magnesium oxide (MgO)
Que: What is the result when the ash (MgO) is mixed with water?
a) Formation of magnesium sulfate
b) Formation of magnesium chloride
c) Formation of magnesium hydroxide
d) Formation of magnesium carbonate
Answer: c) Formation of magnesium hydroxide [Mg(OH)2]
Que: How does the mixture of magnesium oxide and water react with blue and red litmus papers?
a) It turns blue litmus blue
b) It turns blue litmus red
c) It turns red litmus blue
d) It turns red litmus red
Answer: c) It turns red litmus blue
Que: How is the aqueous solution formed by dissolving magnesium oxide in water classified?
a) Acidic
b) Neutral
c) Basic
d) Alkaline
Answer: c) Basic
Que: What substances are formed during the chemical changes involving magnesium?
a) Magnesium chloride and magnesium sulfate
b) Magnesium oxide and magnesium hydroxide
c) Magnesium carbonate and magnesium nitrate
d) Magnesium bromide and magnesium iodide
Answer: b) Magnesium oxide and magnesium hydroxide
Que: What happens when baking soda is added to vinegar?
a) They form a solid precipitate
b) They produce carbon dioxide gas
c) They dissolve completely in water
d) They form a new liquid substance
Answer: b) They produce carbon dioxide gas
Que: What is the result when carbon dioxide gas is passed through lime water?
a) It forms vinegar
b) It forms baking soda
c) It turns lime water milky
d) It changes the color of lime water to blue
Answer: c) It turns lime water milky
Que: Which equation represents the chemical change between carbon dioxide and lime water?
a) Carbon dioxide (CO2) + Lime water [Ca(OH)2] → Calcium carbonate (CaCO3) + Water (H2O)
b) Carbon dioxide (CO2) + Lime water [Ca(OH)2] → Vinegar (CH3COOH) + Water (H2O)
c) Carbon dioxide (CO2) + Lime water [Ca(OH)2] → Sodium chloride (NaCl) + Water (H2O)
d) Carbon dioxide (CO2) + Lime water [Ca(OH)2] → Hydrochloric acid (HCl) + Water (H2O)
Answer: a) Carbon dioxide (CO2) + Lime water [Ca(OH)2] → Calcium carbonate (CaCO3) + Water (H2O)
