Question

Which one of the following pairs of substances on reaction will not evolve $H_2$ gas?

• A. Iron and $H_{2}S{O}_4$ (aq.)
• B. Iron and steam
• C. Copper and $HCl$ (aq.)
• D. Sodium and ethanol

Answer 1

The correct option is C Copper and $HCl$ (aq.)

Metals generally react with acids to give metal salt and hydrogen gas. However, when testing copper with acids, it was found that no bubbles are produced and the temperature also remained unchanged. This shows that copper does not react with dilute HCl. So, hydrogen gas is also not evolved.