Question 7
An atom of an element X has a mass four times that of a carbon-12 atom. What is the relative atomic mass of X?
The right answer is the one marked above.
48. Ar = 4 × 12 = 48; the mass of the carbon atom is on the top and the bottom, so it cancels.
4 is only the ratio given — it still has to be multiplied by 12. 96 comes from using the factor of 8 from the worked example in the text.