JEE Main · 2022 · 29 Jul 2022 · Shift 2 · States of Matter

'x' g of molecular oxygen (

O_{2}

) is mixed with 200 g of neon (Ne). The total pressure of the nonreactive mixture of

O_{2}

and Ne in the cylinder is 25 bar. The partial pressure of Ne is 20 bar at the same temperature and volume. The value of 'x' is ______.
[Given: Molar mass of

O_{2} = 32 g mol^{- 1}

.
Molar mass of

Ne = 20 g mol^{- 1}

]

Answer: 80

Solution

Using Dalton's law:

P_{total} = P_{O X_{2}} + P_{Ne}

. Given

P_{total} = 25

bar and

P_{Ne} = 20

bar, so

P_{O X_{2}} = 5

bar.

Using the relation

P_{O X_{2}} = χ_{O X_{2}} \times P_{total}

, where

χ_{O X_{2}}

is the mole fraction:

\frac{5}{25} = \frac{n _{O X_{2}}}{n _{O X_{2}} + n _{Ne}}

Moles of Ne:

n_{Ne} = \frac{200}{20} = 10

mol

\frac{1}{5} = \frac{x /32}{x /32 + 10}

Cross-multiplying:

x /32 + 10 = 5 x /32

10 = 4 x /32 = x /8

x = 80

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Integer answer

Practise more: all JEE Main PYQs on States of Matter →

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · States of Matter

Solution

More JEE Main questions on States of Matter