The element which forms oxides in all oxidation states from $+I$ to $+V$ is

$HNO_3 + P_4O_{10} \to 4HPO_3 + X$. $X$ is

Regarding the hydrides of group $15$ elements $EH_{3}$ $(E = N, P, As, Sb, Bi)$,select the correct statement from the following:
$A$. The stability of hydrides decreases down the group.
$B$. The basicity of hydrides decreases down the group.
$C$. The reducing character increases down the group.
$D$. The boiling point increases down the group.
Choose the correct answer from the options given below:

Which of the following reactions is a part of the large-scale industrial preparation of nitric acid?

When a brown compound of manganese $(A)$ is treated with $HCl$,it gives a gas $(B)$. The gas taken in excess,reacts with $NH_3$ to give an explosive compound $(C)$. Identify compounds $A$,$B$,and $C$.

Which of the following is an acidic oxide?