Chapter DP, Problem 1PQ

Interpretation Introduction

Interpretation:

The metal that produces hydrogen gas when reacted to concentrated sodium hydroxide has to be given.

Answer to Problem 1PQ

Aluminium produces hydrogen gas when reacted with concentrated sodium hydroxide.  Hence, option (A) is correct.

Explanation of Solution

Reasons for correct option:

Aluminium is amphoteric, which means it can acts as both an acid and a base.

Sodium hydroxide would react with aluminium to form sodium aluminate and hydrogen gas is released.  The chemical reaction is,

  ${\text{2Al+2NaOH+2H}}_{\text{2}}\text{O}\stackrel{}{\to }{\text{2NaAlO}}_2{\text{+3H}}_{\text{2}}$

Hence, the option (A) is correct.

Reasons for incorrect option:

Sodium hydroxide does not attack iron at room temperature, since iron does not have amphoteric properties.  Hence, option (c) is incorrect.

Under normal conditions, magnesium does not react with sodium hydroxide and upon reaction magnesium hydroxide and sodium metal is formed.

  $\text{Mg+2NaOH}\stackrel{}{\to }\text{2Na+Mg}{\left(\text{OH}\right)}_{\text{2}}$

Hence, option (d) is incorrect.

Copper is unreactive and sodium is highly reactive.  Under normal conditions, copper does not react with sodium hydroxide.  Hence, option (b) is incorrect.