Sodium nitrite is reacted with $H_2SO_4$ to form $NaHSO_4$,$HNO_3$,water and $X$. Gold is dissolved in aqua regia to form water,$AuCl_4^{-}$ and $Y$. $X$ and $Y$ are respectively

The element that does $NOT$ exhibit allotropy is$-$

The correct decreasing order of basicity of hydrides of group-$15$ elements is

The correct order of reducing abilities of hydrides of group $15$ elements is:

Choose the correct statements about the hydrides of group $15$ elements.
$A$. The stability of the hydrides decreases in the order $NH_3 > PH_3 > AsH_3 > SbH_3 > BiH_3$
$B$. The reducing ability of the hydrides increases in the order $NH_3 < PH_3 < AsH_3 < SbH_3 < BiH_3$
$C$. Among the hydrides,$NH_3$ is strong reducing agent while $BiH_3$ is mild reducing agent.
$D$. The basicity of the hydrides increases in the order $NH_3 < PH_3 < AsH_3 < SbH_3 < BiH_3$
Choose the most appropriate from the option given below:

The reaction that does not produce nitrogen is