Question

Deduce the number of neutrons from the atomic number (Z) and mass number (A). [3 marks]

Answer 1

Atomic number (Z) is equal to the number of protons present in the nucleus of an atom. [0.5 marks]
Mass number (A) is equal to the sum of the number of protons and neutrons present in the nucleus of an atom. [0.5 marks]
If the number of protons in the nucleus = p and neutrons = n.
So, Z = p and A = n+p [1 marks]
A - Z = n.
So the value of the number of neutrons present in the nucleus of an atom = n = A - Z. [1 marks]