There is a fault in the question. The ratios do not add up as seen in the calculations below.
Moles of Ca 30/40.1 = 0.748 (3sf)
Moles of H 5.05/1= 5.05
molar ratios (divide both sides by 0.748)
Ca:H
1: 6.75 = 2:13.5 = 4:27
Therefore Ca4H27.
This gives a molar mass of 160.4+27= 187.4. Either the mass of hydrogen or the mass of calcium is wrong.
