Which of the following is an amphoteric oxide?

When $NH_3$ reacts with $Cl_2$,which of the following statements are correct?
$(a)$ $NCl_3$ is formed when $Cl_2$ is in excess.
$(b)$ $N_2$ is formed when $Cl_2$ is in excess.
$(c)$ $N_2$ is formed when $NH_3$ is in excess.
$(d)$ $NCl_3$ is formed when $NH_3$ is in excess.

$Ge(II)$ compounds are powerful reducing agents whereas $Pb(IV)$ compounds are strong oxidants. This can be attributed to:

In which of the following options do all species contain $X-O-X$ bonds in their structure ($X =$ central atom)?

Discuss the trends in chemical reactivity of group $15$ elements.

Concentrated $HNO_3$ is a yellow-colored liquid due to: