Which among the group $15$ elements does $NOT$ exist as a tetra-atomic molecule?

Dilute nitric acid on reaction with $Ag$ liberates

Which of the following elements forms oxides in all oxidation states from $+I$ to $+V$?

Which of the following is the anhydride of orthophosphoric acid $(H_3PO_4)$?

Given below are the two statements: one is labeled as Assertion $(A)$ and the other is labeled as Reason $(R)$.
Assertion $(A)$: There is a considerable increase in covalent radius from $N$ to $P$. However,from $As$ to $Bi$,only a small increase in covalent radius is observed.
Reason $(R)$: Covalent and ionic radii in a particular oxidation state increase down the group.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following statements is $NOT$ correct?