Explain the occurrence of elements of group-$15$.

(N/A) $(i)$ Nitrogen: Molecular nitrogen comprises $78\%$ by volume of the atmosphere. In the earth's crust,it occurs as sodium nitrate,$NaNO_{3}$ (chile saltpetre),and potassium nitrate,$KNO_{3}$ (Indian saltpetre). It is also found in the form of proteins in plants and animals.
$(ii)$ Phosphorus: Phosphorus occurs in minerals of the apatite family,$Ca_{9}(PO_{4})_{6} \cdot CaX_{2}$ (where $X = F, Cl, \text{or } OH$). For example,Fluorapatite $[Ca_{9}(PO_{4})_{6} \cdot CaF_{2}]$,Chlorapatite $[Ca_{9}(PO_{4})_{6} \cdot CaCl_{2}]$,and Hydroxyapatite $[Ca_{9}(PO_{4})_{6} \cdot Ca(OH)_{2}]$ are main components of phosphate rocks. Phosphorus is an essential constituent of animal and plant matter,present in bones and living cells. Phosphoproteins are present in milk and eggs.
$(iii)$ Arsenic,antimony,and bismuth are found mainly as sulphide minerals.
$(iv)$ Moscovium: It is a synthetic radioactive element with atomic mass-$289$ and a very short half-life. Due to its short half-life,it is available in very small amounts.