An X molal solution of a compound in Benzene has mole fraction of solute equal to.0.2. The value of X is??

[AC ch5 pg 31 Q24]

mol fraction of solute=0.2
hence mol fraction of benzene=1-0.2=0.8
it means that 0.8 mol of benzene contains 0.2 mol of solute.
.................⇒0.8*78g of benzene contains 0.2 moles of solute
⇒ 62.4g.................................0.2mol...............
⇒1g......................................(0.2/62.4)mol.......
hence 1000g of benzene would contain (1000/62.4)*0.2 mol of solute=3.2=molality of solute=x

1-0.4=0.60.6×78=46.846.8..........0.4mol1g =0.4/46.8=0.008547So, 1000g=0.008547×1000=8.547molality

Dear Student

Xmolal meansXmoles in 1kg benzene.

For further solution please see the solution in the attachment.

I hope this answer will help you.
Thanks & Regards
Yash Chourasiya