2 ml of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolved which is bubbled through a soap solution before testing.
Write a test to detect the gas.

Explanation

Test to detect `H_2` gas : When burning matchstick is kept on the mouth of this test tude, pop soubd is heard which confirms the presence of `H_2` gas.