Question

If the number of protons and neutrons of an element is 13 and 14 respectively, then what’s the atomic number(Z) and mass number(A)?

(a) 13, 13

(b) 13, 27

(c) 14, 13

(d) 27, 14

This question was addressed to me in an interview for job.

Question is taken from Atomic Models topic in division Structure of Atom of Chemistry – Class 11

Answer 1

Right choice is (b) 13, 27

The best I can explain: For an element, Atomic number(Z) = number of protons in that atoms = numbers of electrons in that atom; Mass number = number of protons + number of neutrons. So Z = 13 and A = 13 + 14 = 27. Hence that element is Aluminium.