Which element of group $14$ decomposes steam to form dioxide and dihydrogen gas?

The bleaching action of bleaching powder is due to the liberation of

$Na_2CO_3$ reacts with $SO_2$ in an alkaline medium to form:

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Carbon forms two important oxides $- CO$ and $CO_2$. $CO$ is neutral whereas $CO_2$ is acidic in nature.
Reason $R$: $CO_2$ can combine with water in a limited way to form carbonic acid,while $CO$ is sparingly soluble in water.
In the light of the above statements,choose the most appropriate answer from the options given below:

How is $H_2S$ liberated in the laboratory?

Give uses of carbon dioxide.