Chemistry · Oct / Nov 2019 · Paper 12 · Question 3

The nucleon number of an atom is typically greater than its proton number. The difference between these two numbers indicates the number of ......1...... in the atom. Atoms that have different nucleon numbers but the same proton number are called ......2...... . Which words correctly complete gaps 1 and 2?

1. Aelectrons, isomers
2. Belectrons, isotopes
3. Cneutrons, isomers
4. Dneutrons, isotopes

As printed in the paper