Assertion (A): Pure nitric acid on standing for long turns yellow.
Reason (R): `HNO_(3)` undergoes decomposition and forms `NO_(2)`.

Options

A. Both A and R is true and R is the correct explanation for A.
B. Both A and R are true but R is not the correct explanation for A.
C. A is true and R is false.
D. A is false and R is true.

Answer

A

Explanation

Pure nitric acid on standing for long turns yellow due to its decomposition and the formation of `NO_(2)`, which imparts yellow colour.