Give an example of the following.

A reaction which is a double displacement as well as a precipitation reaction.

Give an example of the following.

A Redox reaction. 

Write the balanced chemical equation for the following reaction & identify the type of reaction.

Nitrogen gas is treated with hydrogen gas in the presence of a catalyst at 773 K to form ammonia gas.

Write the balanced chemical equation for the following reaction & identify the type of reaction.

Sodium hydroxide solution is treated with acetic acid to form sodium acetate & water.

Write the balanced chemical equation for the following reaction & identify the type of reaction.

Ethanol is warmed with ethanoic acid to form ethyl acetate in the presence of concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$.

Write the characteristic tests for the ${\mathrm{CO}}_2$ gas.

Write the characteristic test for the ${\mathrm{H}}_2$ gas.

You could have noted that when copper powder is heated in a china dish the surface of copper becomes black coloured.

Why has this black coloured substance formed?

You could have noted that when copper powder is heated in a china dish the surface of copper becomes black coloured.

What is the black substance?