The atomic number of an element Y is 17. The number of electrons in its ion Y− will be
(a) 17 (b) 18 (c) 19 (d) 20
Answer :
(b) 18
Anion Y− has one more electron than its neutral atom. Y atom has 17 electrons and therefore, in Y−, the number of electrons will be 18 (17 + 1).