2017 H2 Chem P1 Q2 — Atomic structure Solution

The answer is B (1 and 2 only).
Rounding each relative atomic mass to the nearest whole number gives the most common isotopes: \(^7_3\text{Li}\), \(^9_4\text{Be}\), \(^{11}_5\text{B}\), \(^{12}_6\text{C}\), \(^{14}_7\text{N}\), \(^{16}_8\text{O}\), \(^{19}_9\text{F}\), \(^{20}_{10}\text{Ne}\), \(^{23}_{11}\text{Na}\), \(^{24}_{12}\text{Mg}\). Number of neutrons = nucleon number minus proton number.
• Statement 1 is true: \(^7_3\text{Li}\) (4 n, 3 p), \(^9_4\text{Be}\) (5 n, 4 p), \(^{11}_5\text{B}\) (6 n, 5 p), \(^{19}_9\text{F}\) (10 n, 9 p) and \(^{23}_{11}\text{Na}\) (12 n, 11 p) all have more neutrons than protons.
• Statement 2 is true: \(^{12}_6\text{C}\), \(^{14}_7\text{N}\), \(^{16}_8\text{O}\), \(^{20}_{10}\text{Ne}\) and \(^{24}_{12}\text{Mg}\) have equal numbers of neutrons and protons.
• Statement 3 is false: none of the ten isotopes has fewer neutrons than protons.
• A is wrong: it includes statement 3, which is false.
• C is wrong: it includes the false statement 3 and leaves out the true statement 1.
• D is wrong: it leaves out the true statement 1.