Question

The number of electrons, protons and neutrons in a species are equal to $18$, $16$ and $16$ respectively. Assign the proper symbol to the species.

• (A) ${}_{18}^{32}{\mathrm{S}}^{2-}$
• (B) ${}_{16}^{32}{\mathrm{Ca}}^{2-}$
• (C) ${}_{16}^{32}{\mathrm{P}}^{2-}$
• (D) ${}_{16}^{32}{\mathrm{S}}^{2-}$

Answer 1

The Correct Option is D

Explanation:
The atomic number is equal to number of protons $=16$. The element is sulphur (S).Atomic mass number $=$ number of protons $+$ number of neutrons$=16+16=32$Species is not neutral as the number of protons is not equal to electrons. It is anion (negatively charged) with charge equal to excess electrons $=18–16=2$Thus symbol is ${}_{16}^{32}{\mathrm{S}}^{2-}$.Hence, the correct option is (D).