Question

Write the test for the gas which is evoled when hydrochloric acid reacts with an active metal.

Answer 1

Hydrogen gas is evolved when hydrochloric acid reacts with an active metal such as sodium, potassium, calcium or magnesium.

$Mg\left(s\right)+2HCl\left(aq\right)\to MgC{l}_2\left(aq\right)+H_2\left(g\right)$

To test the presence of hydrogen gas bring a burning match stick or a candle near it. Hydrogen being inflammable will immediately catch fire.