Question

The ion of an element has 3 positive charges. The mass number of atom of this element is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

(a) 13

(b) 10

(c) 14

(d) 16

Answer 1

(b) 10
Mass number of the element = 27
Number of neutrons = 14
Number of protons = mass number – number of neutrons
= 27 – 14 = 13
As the ion of this element has 3 positive charges, it means that it has lost 3 electrons. Therefore, there are now 10 electrons in the ion.