Question

What is the total number of electrons in a S2– ion? (1) 10 (3) 16 (2) 14 (4) 18

Answer 1

Sulfur normally has 16 electrons (see the periodic table), but the 2- indicates that the atom is gaining 2 electrons. because of that, the answer would be 18.
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Answer 2

Answer:  (4) 18

Explanation: $S^{2-}$ is an anion formed when neutral sulfur atom gains two electrons.

Sulfur (S) is an element with atomic number of 16. Thus it contains 16 electrons.

S: $1s^22s^22p^63s^23p^4$

It gains two electrons, the number of electrons increase to 18 and attain a stable configuration.

$S^{2-}:1s^22s^22p^63s^23p^6$