Question

Name the following-

1.A metal which is used as reactant in the laboratory preparation of hydrogen-

2-A metal which floats on the surface of cold water and reacts with it to form hydrogen gas-

3.A metal which sinks in cold water and reacts with it to form hydrogen gas-

Answer 1

1. Zinc is the metal used to prepare H₂ in laboratory.
2. Lithium
The density of Lithium is only about half to that of water, so it floats on the surface and reacts with water to give hydrogen gas
3. Rubidium
Rubidium sinks because it is less dense than water. ​It reacts with water to form Rubidium hydroxide and hydrogen are formed.