A solution is made by mixing one mole of volatile liquid \( A \) with \( 3 \) moles of volatile liquid \( B \). The vapour pressure of pure \( A \) is \( 200 \, \text{mm Hg} \) and that of the solution is \( 500 \, \text{mm Hg} \). The vapour pressure of pure \( B \) and the least volatile component of the solution, respectively, are:
