Which among the following group-$15$ elements forms hydrogen bonding in its hydride compounds?

Which of the following compounds is the most acidic?

Phosphorus has three allotropic forms:
$(i)$ white phosphorus
$(ii)$ red phosphorus and
$(iii)$ black phosphorus.
Write the difference between white and red phosphorus on the basis of their structure and reactivity.

What is produced when $Ag$ is heated with concentrated $HNO_3$?

In the following reaction,identify the nature of the products formed by the complete hydrolysis of $\underline{P}_4O_8$ at $R.T$:
$\underline{P}_4O_8 + H_2O \longrightarrow H_3PO_3 + H_3PO_4$

Which of the following elements of group $15$ $(VA)$ does not show allotropy?