At $35^{\circ}\mathrm{C}$, the vapour pressure of $\mathrm{CS}_{2}$ is 512 mm of Hg and that of acetone is 344 mm of Hg. A solution of $\mathrm{CS}_{2}$ in acetone has a total vapour pressure of 600 mm of Hg. The false statement among the following is

(D) a mixture of $100\mathrm{~mL}$ $\mathrm{CS}_{2}$ and 100 mL acetone has a volume of $<200\mathrm{~mL}$

(A) $\mathrm{CS}_{2}$ and acetone are less attracted to each other than to themselves

(B) Heat must be absorbed in order to produce the solution at $35^{\circ}\mathrm{C}$

(C) Raoult's law is not obeyed by this system

JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Solutions

3 5^{\circ} C

, the vapour pressure of

CS_{2}

is 512 mm of Hg and that of acetone is 344 mm of Hg. A solution of

CS_{2}

in acetone has a total vapour pressure of 600 mm of Hg. The false statement among the following is

(A) $CS_{2}$ and acetone are less attracted to each other than to themselves
(B)Heat must be absorbed in order to produce the solution at $3 5^{\circ} C$
(C)Raoult's law is not obeyed by this system
(D)a mixture of $100 mL$ $CS_{2}$ and 100 mL acetone has a volume of $< 200 mL$ ✓ Correct

Answer: (D)

Solution

Since the total vapour pressure,

600 mm

, exceeds both pure-component values, the solution shows positive deviation from Raoult's law: unlike molecules attract each other less strongly than like molecules do. Such mixing absorbs heat and is accompanied by a small increase in volume, not a contraction, so the claim that

100 mL

C S_{2}

and

100 mL

of acetone give less than

200 mL

is the false statement.

JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Single correct option

Practise more: all JEE Main PYQs on Solutions →

JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Solutions

Solution

More JEE Main questions on Solutions