GCSE / O Levels Chemistry

Two isotopes of chlorine are 35Cl and ³7 Cl.
Using these isotopes and ¹2C and ¹H, how many different relative molecular masses are possible
for the compound with molecular formula C₂H3C13?
A 2
B 3
C 4
D 5

Choice C is correct because:

 For the compound C2H3Cl3, there are four different relative molecular masses possible due to the presence of three chlorine atoms which can either be 35Cl or 37Cl:

Two ¹²C, three ¹H, and three 35Cl.

Two ¹²C, three ¹H, two 35Cl and one 37Cl.

Two ¹²C, three ¹H, one 35Cl and two 37Cl.

Two ¹²C, three ¹H, and three 37Cl.

Choices A, B and D are incorrect because they do not represent the correct number of relative molecular masses possible for C2H3Cl3 given the presence of chlorine isotopes (35Cl and 37Cl).

Relative Masses of Atoms and Molecules, Atomic Structure | 2022 - M/J - 5070/11 | Q7