Which of the following is an ionic compound?

How can you explain the higher stability of $BCl_3$ as compared to $TlCl_3$?

Which of the following processes is used for the production of $HNO_3$ to obtain a good yield?

Which of the following elements does not form stable diatomic molecules?

Account for the following observations:
$(A)$ $AlCl_3$ is a Lewis acid.
$(B)$ Though fluorine is more electronegative than chlorine yet $BF_3$ is a weaker Lewis acid than $BCl_3$.
$(C)$ $PbO_2$ is a stronger oxidizing agent than $SnO_2$.
$(D)$ The $+1$ oxidation state of thallium is more stable than its $+3$ state.

Among the members of $V$ $A$ group ($N$,$P$,$As$,$Sb$,and $Bi$),which of the following properties shows an increase as we go down from nitrogen to bismuth?