Which of the following is a chemical change? MCQ with Answer and Explanation

Which of the following is a chemical change?
A. Cooking of food
B. Melting of candle wax
C. Dissolving sugar in water
D. Breaking a glass tumbler
Answer: Option A
Solution (By JKSSB Mock Tests)
Cooking of food involves chemical reactions (e.g., denaturation of proteins, caramelization of sugars) that form new substances, making it a chemical change. Dissolving sugar in water is a physical change because no new substance is formed (sugar can be recovered by evaporation). Breaking glass is a physical change (change in size/shape). Melting wax is a physical change (change of state).

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Practice More chemistry Questions

Question #1
Which of the following isotopes is used in the treatment of blood cancers?
A. Sodium-24
B. Carbon-14
C. Cobalt-60
D. Iodine-131

Correct Answer: Option C


Explanation:
Cobalt-60 is a radioactive isotope that emits strong gamma radiation. It is widely used in radiotherapy to treat various types of cancers, including blood cancers like leukemia. Iodine-131 is used for thyroid disorders, Carbon-14 for radiocarbon dating, and Sodium-24 for detecting blood clots.

This question belongs to: Science chemistry
Question #2
The reaction 2H₂O → 2H₂ + O₂ is a:
A. Double displacement reaction
B. Combination reaction
C. Decomposition reaction
D. Displacement reaction

Correct Answer: Option C


Explanation:
Water breaks down into hydrogen and oxygen when electricity is passed (electrolysis). A single reactant yields two or more products, hence decomposition. It is also a redox reaction. Combination is the opposite; displacement involves replacing an ion.

This question belongs to: Science chemistry
Question #3
Which allotrope of carbon is used as a neutron moderator in nuclear reactors?
A. Diamond
B. Graphite
C. Fullerene
D. Charcoal

Correct Answer: Option B


Explanation:
Graphite slows down fast neutrons in nuclear reactors, enabling sustained chain reaction. Diamond is hard and insulating; fullerenes are nanomaterials; charcoal is adsorbent.

This question belongs to: Science chemistry