Chemical Changes Quiz - CBSE Class 7 Science

Free practice quiz: Chemical Changes (CBSE Class 7 Science). 20 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following is a chemical change?

   1. Melting of ice
   2. Rusting of iron
   3. Boiling of water
   4. Mixing sand and salt
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   Answer: B. Rusting of iron

   Rusting of iron is a chemical change because new substances are formed during this process.

2. Which gas is commonly produced during a chemical reaction that involves burning?

   1. Hydrogen
   2. Oxygen
   3. Carbon dioxide
   4. Nitrogen
   Show answer

   Answer: C. Carbon dioxide

   Carbon dioxide is a common gas produced during combustion reactions, such as burning fossil fuels.

3. What is the process of tarnishing of silver?

   1. Physical change
   2. Chemical change
   3. Both physical and chemical changes
   4. No change
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   Answer: B. Chemical change

   Tarnishing of silver is a chemical change due to a reaction with sulfur compounds, forming silver sulfide.

4. What happens when a compound decomposes?

   1. Forms a mixture
   2. Breaks into simpler substances
   3. Changes in color
   4. Changes state
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   Answer: B. Breaks into simpler substances

   Decomposition involves breaking a compound into simpler substances through chemical reactions.

5. Why does baking a cake represent a chemical change?

   1. Only heat is involved
   2. New smell is produced
   3. New substances are formed
   4. Color changes
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   Answer: C. New substances are formed

   Baking a cake involves chemical reactions that form new substances, such as when baking soda releases carbon dioxide and interacts with other ingredients.

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