A sample of a substance with the empirical formula xcl3

Question

A sample of a substance with the empirical formula XCl₃ weighs 0.5292 g. When it is dissolved in water and all its chlorine is converted to insoluble AgCl by addition of an excess of silver nitrate, the mass of the resulting AgCl is found to be 1.4026 g. The chemical reaction is

XCl₃ + 3 AgNO₃3AgCl + X(NO₃)₃

(a) Calculate the formula mass of XCl₃.

Formula mass XCl₃ =  g mol^-1

(b) Calculate the atomic mass of X. 

Atomic mass X =  g mol^-1