JEE Main 26-Aug-2021 Shift 1 Solved Paper

Density of solution =

Mass‌of‌solution

Volume‌of‌solution

1.20g∕mL=

Mass‌of‌solution

Volume‌of‌solution

...(ii)
As molality =3.3‌mol∕kg
that means 3.3 moles of KCl present in 1‌kg of solvent.
∴ 1000g of solvent has 3.3×74.5g of KCl=245.8g
∴ Weight of solution = weight of solute + Weight of solvent
=245.85g+1000g=1245.85g
From Eqs. (ii)
Volume of solution =

Mass‌of‌solution

1.20g∕mL

=

1245.85g

1.20g∕mL

=1038.2‌mL
From Eq. (i)
Molarity =

245.85g

74.5g

×

1

1038.2‌mL

×1000 =3.17‌mol∕L
∴ Molarity of solution in mol∕L‌is‌3.17
Answer = 3