Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): Fixation and release of \(\text{K}^+\) in soil is influenced by absence or presence of ammonium ion (\(\text{NH}_4^+\)).
Reason (R): The physics of \(\text{NH}_4^+\) is closely related to that of \(\text{K}^+\) because both ions have similar ionic radii and low hydration energy.
Choose the correct answer from the options given below:

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

Hint:

Because of their similar ionic size (\(\text{K}^+ = 1.38 \text{ \AA}\) and \(\text{NH}_4^+ = 1.43 \text{ \AA}\)), these two ions compete for the same interlayer fixation sites in 2:1 clay minerals.

Answer 1

The Correct Option is A