Question

Which of the following are true for an element? [1 mark]

(i) Atomic number = number of protons + number of electrons
(ii) Mass number = number of protons + number of neutrons
(iii) Atomic mass = number of protons = number of neutrons
(iv) Atomic number = number of protons = number of electrons

(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)

[1 mark]

Answer 1

The correct option is (d) (ii) and (iv). [1 mark]

• Mass number is the sum of the number of protons and number of neutrons.
• Atomic number is equal to the number of protons and number of electrons of the neutral atom.