Question

Which metal reacts with concentrated naoh to produce hydrogen gas?

Answer 1

The metal which react with concentrated sodium hydroxide to produce hydrogen gas is ALUMINIUM. 
The equation of the reaction is as follows:
2AL + 2NaOH + 2H2O = 2 NaALO2 + 3H.
The product formed is called sodium aluminate. The reaction is an exothermic reaction and is accompany by the evolution of hydrogen gas.

Answer 2

Answer:

Aluminium would readily react with NaOH to produce Hydrogen gas.

Explanation:

Options;

A) Aluminum B) Copper C) Iron D) Magnesium

Sodium hydroxide does not attack iron at room temperatures, since iron does not have amphoteric properties (i.e., it only dissolves in acid, not base). Nevertheless, at high temperatures (e.g. above 500 °C), iron can react endothermically with sodium hydroxide to form iron(III) oxide, sodium metal, and hydrogen gas.

The reaction is given as;

4Fe + NaOH --> Fe2O3 + 6Na + 3H2

NaOH would react with Aluminium to form Sodium silicate and Hydrogen gas as given in the reaction below;

2Al + 2NaOH + 6H2O --> 2NaAl(OH)4 + 3H2

Under normal conditions, magnesium do not react with NaOH and when it does the reaction is given as;

Mg + 2 NaOH → 2 Na + Mg(OH)2

Copper is quite unreactive, and sodium is very reactive. To displace the sodium, the reaction would have a very high activation energy. As such, under normal conditions, copper does not react with NaOH.