CSEC Chemistry · May/June 2016 · Paper 1 · Question Q10

Which of the following pairs of atoms has the same number of neutrons?

1. (A)^{40}_{18}\text{Ar} and ^{40}_{20}\text{Ca}
2. (B)^{31}_{15}\text{P} and ^{32}_{16}\text{S}
3. (C)^{24}_{12}\text{Mg} and ^{12}_6\text{C}
4. (D)^{16}_8\text{O} and ^{19}_9\text{F}