Q1. Concentrated nitric acid (aq) reacts with copper to give:
A Copper nitrate and hydrogen gas
B Copper nitrate, nitrogen monoxide and water
C Copper nitrate, nitrogen dioxide and water Correct
D Copper oxide and dinitrogen oxide
Explanation
Copper reacts with concentrated aqueous nitric acid in a redox reaction. Copper is oxidised to copper nitrate, while concentrated nitric acid is reduced mainly to nitrogen dioxide, a brown gas, and water is also formed. Hydrogen gas is not released because nitric acid is a strong oxidising acid, unlike dilute non-oxidising acids. Nitrogen monoxide is the usual product with dilute nitric acid, not concentrated nitric acid. Copper oxide and dinitrogen oxide do not represent the standard reaction products for copper with concentrated nitric acid.