Question

A gas occupies 1.5 litres volume at 75 cm Hg
pressure. At the same temperature what will be
the volume of gas at 50 cm Hg pressure
(A) 1.25 liters
(B) 3.25 liters
(C) 4.25 liters
(D) 2.25 liters​

Answer 1

Given :-

$\sf V_1$ = 1.5 L

$\sf P_1$ = 75 cm hg

$\sf P_2$ = 50 cm hg

To Find :-

$\sf V_2$

Solution :-

According to Boyle's law :-

For a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional.

PV is a constant

So,

$\bf P_1 \times V_1 = P_2 \times V_2$

Substitute the values :-

$: \implies \sf 75 \times 1.5 = 50 \times V_2$

$: \implies \sf 112.5 =50 \times V_2$

$: \implies \sf V_2 = \dfrac{112.5}{50}$

$\sf : \implies V_2 = \dfrac{9}{4}$

$: \implies \bf V_2 = 2.25L$

Correct option :- D

Answer 2

Given :-

A  gas occupies 1.5 litres volume at 75 cm Hg  pressure.

To Find :-

At the same temperature what will be  the volume of gas at 50 cm Hg pressure

Solution :-

Pressure is constant

P₁V₁ = P₂V₂  

V₂ = P₁V₁/P₂

V₂ = 1.5 × 75/50

V₂ = 112.5/50 × 1/10

V₂ = 1125/500

V₂ = 2.25 L

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