Question

2.
A metal powder was added to dil. HCl and dil. NaOH solutions taken in separate test tubes. On
making the contents react in both the test tubes, hydrogen gas was formed in both the cases. The
metal used will be:
(a) Cu
(b) Zn
(c) Fe
(d) Pb
​

Answer 1

Zn on reaction with HCl and NaOH releases hydrogen gas.

The equation for both reactions are as follows:

1. Zn+ 2NaOH -----> Na2ZnO2 + H2

2. Zn + 2HCl ----------> ZnCl2 + H2

Answer 2

A metal powder was added to dil. HCl and dil.NaOH soultion taken in separate tubes. On making the contents react in both tubes, hydrogen gas was formed in both cases. Then the metal used is Zn i.e zinc

1. Zinc granules give hydrogen gas; along with zinc chloride; when they react with hydrochloric acid.
2. Zn + 2HCl ⇨ ZnCl2 + H2
3. If sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated, sodium zincate is formed along with hydrogen gas.
4. Zn + 2NaOH ⇨ Na2ZnO2 + H2