Which of the following reactions can produce hydrogen gas?

Hydrogen can be obtained from water,by the action of water on

Given below are two statements :
Statement-$I$: Methane and steam passed over a heated $Ni$ catalyst produces hydrogen gas.
Statement-$II$: Sodium nitrite reacts with $NH_4Cl$ to give $H_2O$,$N_2$ and $NaCl$.
In the light of the above statements,choose the most appropriate answer from the options given below :

The charring of sugar takes place when treated with concentrated $H_2SO_4$. What is the type of reaction involved in it?

Which of the following is not an isotope of hydrogen?

Fire extinguishers contain $H_2SO_4$ and