$H_2C_2O_4 \xrightarrow{\Delta} \text{gas } (A) + \text{gas } (B) + \text{liquid } (C)$.
Gas $(A)$ burns with a blue flame and is oxidised to gas $(B)$.
Gas $(A) + Cl_2 \to (D)$.
$A, B$ and $D$ are:

Which of the following fuels has the maximum calorific value per gram?

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 :

Which set of elements forms stable,covalent,and hydrogen-bonded hydrides?

Which of the following methods is used to prepare dihydrogen with purity greater than $99.95 \%$?

Among the following,the correct statements are:
$I$. $LiH, BeH_2$ and $MgH_2$ are saline hydrides with significant covalent character.
$II$. Saline hydrides are volatile.
$III$. Electron-precise hydrides are Lewis bases.
$IV$. The formula for chromium hydride is $CrH$.
The correct option is: