Question

Assertion (A): Ozone at higher levels of atmosphere is a product of UV radiation acting on oxygen molecule.
Reason (R): The higher energy of UV splits apart some molecular \( O_2 \).

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Ozone formation in stratosphere: \[ O_2 \xrightarrow{UV} 2O \] \[ O + O_2 \rightarrow O_3 \] UV radiation is essential for both splitting oxygen and forming ozone!

Answer 1

The Correct Option is A

To determine the validity of the assertion and reason, let's analyze each statement step-by-step:

1. Assertion (A): Ozone at higher levels of atmosphere is a product of UV radiation acting on oxygen molecule.
   • In the stratosphere, ozone is formed by the action of ultraviolet (UV) radiation on molecular oxygen \(( \text{O}_2 )\).
   • This process involves the splitting of molecular oxygen into individual oxygen atoms due to the energy provided by UV radiation. The free oxygen atoms then combine with molecular oxygen to form ozone \(( \text{O}_3 )\).
   • Therefore, the assertion is true.
2. Reason (R): The higher energy of UV splits apart some molecular \(( \text{O}_2 )\).
   • When UV radiation reaches the stratosphere, its energy is sufficient to break the bond in molecular oxygen \(( \text{O}_2 )\), producing two separate oxygen atoms.
   • These free oxygen atoms are highly reactive and can combine with other molecular oxygen to form ozone \(( \text{O}_3 )\).
   • Therefore, the reason is also true and it correctly explains the process mentioned in the assertion.

The reason effectively explains the process described in the assertion. UV radiation's role in both splitting \(\text{O}_2\) molecules and facilitating the formation of ozone makes it a correct and direct link. Therefore, the given correct answer is:

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).