Question

Select from the following a decomposition reaction in which the source of energy for decomposition is light:

• A. 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃
• B. 2H₂O → 2H₂ + O₂
• C. 2AgBr → 2Ag + Br₂
• D. CaCO₃ → CaO + CO₂

Answer 1

The Correct Option is C

Step 1: Understanding Photolysis:
Photolysis refers to a decomposition reaction that is driven by light energy. In this process, light energy is absorbed by a substance, causing it to break down into simpler compounds.

Step 2: Decomposition of Silver Bromide (AgBr):
One example of photolysis is the decomposition of silver bromide (AgBr) under light. When exposed to light, silver bromide breaks down into two simpler products: silver (Ag) and bromine (Br₂). The balanced chemical equation for this reaction is:
\[ 2\text{AgBr} \rightarrow 2\text{Ag} + \text{Br}_2 \]

Step 3: Application of the Photolysis Reaction in Photography:
This photolysis reaction is extensively used in photographic films. In a photographic film, silver halides like silver bromide (AgBr) are present. When the film is exposed to light, the silver bromide decomposes into silver (Ag) and bromine (Br₂). The silver then forms an image on the film.

Step 4: Conclusion:
The photolysis of silver bromide is a key reaction in photography, as it allows for the creation of images on film when exposed to light.