The hydride ion $H^{-}$ is isoelectronic with which of the following?

Hydrogen has three isotopes $(A)$,$(B)$ and $(C)$. If the number of neutron$(s)$ in $(A)$,$(B)$ and $(C)$ respectively,are $(x)$,$(y)$ and $(z)$,the sum of $(x)$,$(y)$ and $(z)$ is:

Asthma patients use a mixture of $.....$ for respiration.

Water gas is

When conc. $H_2SO_4$ comes in contact with sugar,it becomes black due to

Carbongene has $X\%$ of $CO_2$ and is used as an antidote for poisoning of $Y.$ Then,$X$ and $Y$ are