Asolution is made from 50.0 g ccl4 and 50.0 g chcl3. what is the mole fraction of carbon tetrachloride (ccl4) in the solution? (molar masses are ccl4 = 153.8 g/mol; chcl3 = 119.4 g/mol)

Moles of the molecule = mass of the molecule / molar mass.
Therefore, the moles of CCl4 = 50.0g/153.8g/mol = 0.325 mol, and the moles of CHCl3 = 50.0g/119.4g/mol = 0.419 mol. 
The mole fraction of CCl4 = moles of CCl4 / (moles of CCl4 + moles of CHCl3) = 0.325 mol / (0.325mol+0.419mol) = 43.7%

The mole fraction of carbon tetrachloride in the solution is 43.7%.