Name the gas evolved when metals are made to react with dilute acids

Gas evolved is hydrogen

1) When a metal reacts with a dilute acid like HCl, HNO3 etc. hydrogen gas is evolved. The reaction can be shown as follows:

2M + dil. 2HCl → 2MCl + H2↑

Hydrogen gas can be identified by bringing a burning matchstick near the mouth of the test tube in which reaction takes place. Hydrogen gas will burn with a pop sound.

2) Sulphur burns in oxygen to form SO2(sulphur dioxide) gas. This gas is acidic and turns a damp blue litmus paper to red.
S + O2 → SO2