Question

Explain the method of preparation of hydrogen gas in laboratory with chemical equation and diagram.

Answer 1

In a conical flask, fitted with the delivery tube, few grams of granulated zinc is taken. Then dil. $HCl$ is added. Zinc reacts with $HCl$ to form zinc chloride and hydrogen gas.
$Zn+2HCl\to ZnC{l}_2+H_2\uparrow$.
The liberated hydrogen gas is collected in an inverted test tube placed in a water trough.