AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
(A) Both A and R are true, and R is the correct explanation of A.
HNO₃ is a strong oxidising agent; it oxidises the H₂ produced to water, so hydrogen gas is not evolved when metals react with dilute nitric acid.
The examiner expects the student to know that nitric acid (dilute or concentrated) acts as an oxidising agent and oxidises nascent hydrogen to water, which is why H₂ gas is not liberated — unlike reactions with HCl or H₂SO₄. Both the assertion and the reason are factually correct, and the reason directly explains why hydrogen is not evolved, making option (A) the correct choice.