The element with atomic number $33$ belongs to which group of the periodic table?

In group $15$ of the periodic table,nitrogen forms only a trihalide,but other elements form pentahalides also. The reason is:

Which of the following is a tetrabasic acid?

Which of the following is formed when aluminium oxide and carbon are strongly heated in dry chlorine gas?

White phosphorus,when heated with conc. $NaOH$ solution in an inert atmosphere of $CO_2$,forms phosphine and a sodium salt of oxoacid of phosphorus,$'X'$. The oxidation state of phosphorus in $'X'$ is

In the nitrogen family,the $H-M-H$ bond angle in the hydrides $MH_3$ gradually becomes closer to $90^o$ on going from $N$ to $Sb$. This shows that gradually