Complete the word equation given below:

Metal + dilute acids $\to$salt + ________

The correct option is B

Hydrogen gas

Metals react with dilute acids to form metal salts and hydrogen gas.

Example:

$\underset{\mathrm{Sodium}}{2\mathrm{Na}\left(\mathrm{s}\right)}+\underset{\mathrm{dil}.\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Sodium}\mathrm{chloride}}{2\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$

Hence, the correct answer is option(b).