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ICSE Class 9 Chemistry Question 15 of 18

Chemical Changes and Reactions — Question 16

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16
Question

Question 2(iv)

Assertion (A): The decomposition of silver bromide is utilized in black and white photography.

Reason (R): Light provides energy for this endothermic reaction.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
Answer

Both A and R are true and R is the correct explanation of A.

Explanation — Silver bromide (AgBr) decomposes when exposed to light. The formation of black metallic silver is what creates the image in black and white photography. Hence the assertion (A) is true.

2AgBr →light\xrightarrow{\text{light}} 2Ag + Br

Above reaction is an endothermic reaction where heat is absorbed. Light provides energy for this decomposition of silver bromide. Hence the reason (R) is true and reason (R) is a correct explanation of assertion (A).