Question

3 moles of A and 5 moles of B are added to make a solution. Find its mole fraction for solution A. How many mole of A should be added to the solution to make its mole fraction 0.4?​

Answer 1

moles of A=3

moles of B=5

$xa = \frac{na}{na + nb} \\ xa = \frac{3}{8} = 0.4$

i hope this helps ( ╹▽╹ )