Nitrogen dioxide is dissolved in water to produce

Given below are two statements:
Statement $I$: Like nitrogen that can form ammonia,arsenic can form arsine.
Statement $II$: Antimony cannot form antimony pentoxide.
In the light of the above statements,choose the most appropriate answer from the options given below:

$H_3PO_2$ $\xrightarrow{140^{\circ}C}$ $A$ $\xrightarrow{250^{\circ}C}$ $B$ $\xrightarrow{316^{\circ}C}$ $C$
Compound $(C)$ is

Nitrogen can be obtained from air by removing

Which of the following is an amphoteric oxide?

Write a note on $p$-block elements of the periodic table.