Question

If I is the intensity of absorbed light and C is the concentration of AB for the photochemical process $AB+hv\to AB$ , the rate of formation of AB is directly proportional to
A. C
B. I
C. ${{I}^{2}}$
D. CI

Answer 1

Hint: All chemical reactions are not going to take place through reagents. Few reactions are going to take place by using sunlight. Those chemical reactions are photochemical reactions. Photochemical reactions follow the Beer-Lambert's law.

Complete answer:
- In the question it is asked that the formation of AB in the below reaction is directly proportional to which option among the given options.
\[AB+hv\to AB\]
- Generally photochemical reactions are going to take place in the presence of sunlight.
- In photochemical reaction the rate of the formation of products (AB) is directly proportional to the intensity of the light.
Rate of formation of AB $\propto $ Intensity of the light (I)
- If the intensity of the incident light is less then the rate of the reaction is less.
- If the intensity of the incident light is high then the rate of the reaction is high.
- Therefore, the rate of formation of AB is directly proportional to Intensity of the light (I).

So, the correct option is B.

Note:
In photochemical reaction the incident light or the intensity of the light is going to activate the reactants involved in it. The activated reactants then participate in the chemical reaction and form the product. This type of reaction does not need any reagents to complete the reaction to form the products.