Question

calculate kole fraction of hcl in solution of hcl contaning 24.8% of hcl by mass

Answer 1

% HCl means grams HCl/100 g solution.

24.8% HCl = 24.8 g HCl/(24.8g HCl + 75.2 g H2O)
n HCl = g HCl/molar mass = ?
n H2O = g H2O/molar mass = ?

XHCl = nHCl/total mols.