Question:
Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals
(except Mn and Mg) ?
(a) H2SO4
(b) HCl
(c) HNO3
(d) All of these.
Solution:
(c). HNO3 is a strong oxidising agent. It oxidises metals to metal oxides and then to metal nitrates and itself is reduced to either nitric oxide (NO),
nitruos oxide (N2O) or nitrogen dioxide (NO2). However, both Mg and Mn evolve hydrogen on reacting with the acid.