What is heavy water?

Atoms in hydrogen gas have a preponderance of which isotope?

Which of the following processes can be used to obtain heavy water $(D_2O)$?

$H_2SO_4$ acts as a dehydrating agent in its reaction with:

Select the correct statement regarding interstitial hydrides.

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