Of the following,the non-existent compound is

The decreasing values of bond angles from $NH_3$ $(106^o)$ to $SbH_3$ $(101^o)$ down group-$15$ of the periodic table is due to

Identify the correct orders from the following with respect to the property associated with:
$A$. $NH_3 > PH_3 > AsH_3 > SbH_3$ - Bond Angle
$B$. $NH_3 > PH_3 > AsH_3 > SbH_3$ - Basic Character
$C$. $PH_3 > AsH_3 > SbH_3 > NH_3$ - Thermal stability
$D$. $SbH_3 > NH_3 > AsH_3 > PH_3$ - Boiling point

Give the preparation of Nitric acid $(HNO_3)$. Discuss its physical and chemical properties and state its uses.

Heating $(NH_4)_2Cr_2O_7$ produces a gas. This gas can also be obtained by:

In the nitrogen group,as we move from $N$ to $Sb$,the $H-M-H$ bond angle in the hydrides approaches $90^o$ because ......