Given below are two statements: Assertion (A) and Reason (R). Assertion (A): Soil acidity can be caused due to loss of Calcium & Magnesium salts in areas of high rainfall. Reason (R): CO₂ formed during respiration reacts with water to form carbonic acid which converts bases into soluble forms that are lost through leaching.

Correct option is A

The correct answer is (A) Both (A) and (R) are correct and (R) is the correct explanation of (A)
Explanation: 

Assertion (A):
High rainfall leads to the leaching of basic cations like Ca²⁺ and Mg²⁺.
As these bases are removed from the soil exchange complex, they are replaced by acidic ions such as H⁺ and Al³⁺, resulting in soil acidity.

Reason (R):
Microbes and plant roots release CO₂ ​ during respiration. This CO₂dissolves in soil water to form H₂CO₃ ​ (carbonic acid). The carbonic acid dissociates to release H⁺ ions, which displace Ca²⁺ and Mg²⁺ from soil particles, making them soluble and susceptible to leaching.

• Since the reason provides the direct chemical mechanism for the process mentioned in the assertion, (A) is the correct choice.

Information Booster:
• Acid soils are usually reclaimed by adding 'lime' (Calcium carbonate), which neutralizes $H^{+}$ and replaces $Al^{3+}$ with $Ca^{2+}$.

Additional Knowledge:
• Soil pH: A measure of the acidity or alkalinity of the soil. A pH below 7 is acidic.
• Aluminum Toxicity: In very acidic soils (pH < 5.0), Aluminum becomes soluble and is toxic to most plant roots.