Answer
$47.7\text{ g/mol}$
X is titanium
Work Step by Step
Take the mass percentage of X,
$100.0 - 74.8 = 25.2\%$
Atomic mass of $Cl_{4}$ = $35.5 \times 4 = 142$
Hence by comparing the atomic mass of $Cl_{4}$ and its mass percentage the atomic mass of X can be taken as,
$\frac{25.2\times 144}{74.8} =47.8$
This is approximately equal to $47.7$ and hence X can be identified to be Titanium
