ibsibjbsi has a lot to do about it but it's
<span>Mr = 13 g / mol
mass = 5 g
Mol = 5/13 mol :)</span>
The relationship between pressure and solubility of the gas is given by Henry's law as:

where,
is the solubility of the gas.
is proportionality constant i.e. Henry's constant.
is pressure of the gas.
(given)
(given)
Substituting the values,

To convert
to
:
Molar mass of benzene,
= 

Now for converting into
:
Since, 
So,
.
Hence, the solubility of benzene in water at
in
is
.
Mass percent= grams solute/ grams of solution x 100
Mass Percent= (50/ 150)x100= 33.3%