At 298 K, the mole percentage of N2 (g) in air is 80%. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of N2 (g) in water at 298 K ?
Q. At 298 K, the mole percentage of N₂ (g) in air is 80%. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of N₂ (g) in water at 298 K ? (KH for N₂ is 6.5 × 107 mmHg)

(A) 9.35 × 10−5

(B) 9.35 × 105

(C) 1.23 × 10−7

(D) 1.17 × 10−4

Correct Answer: 9.35 × 10−5

Explanation

According to Henry’s law:

p = KH × x

Mole fraction of N₂ in air = 80% = 0.8

Total pressure = 10 atm

Partial pressure of N₂:

p(N₂) = 0.8 × 10 = 8 atm

Convert pressure into mmHg:

8 atm = 8 × 760 = 6080 mmHg

Given:

KH = 6.5 × 107 mmHg

Using Henry’s law:

x = p / KH

x = 6080 / (6.5 × 107)

x = 9.35 × 10−5

Hence, the mole fraction of N₂ in water is 9.35 × 10−5.

Related JEE Main Questions

The number of possible tripeptides formed involving alanine (ala), glycine (gly) and valine (val), where no amino acid has been used more than once is:
Find out the statements which are not true. A. Resonating structures with more number of covalent bonds and lesser charge separation are more stable. B. In electromeric effect, an unsaturated system shows +E effect with nucleophile and −E effect with electrophile. C. Inductive effect is responsible for high melting point, boiling point and dipole moment of polar compounds. D. The greater the number of alkyl groups attached to the doubly bonded carbon atoms, higher is the heat of hydrogenation. E. Stability of carbanion increases with the increase in s–character of the carbon carrying the negative charge.
One mole of Cl₂ (g) was passed into 2 L of cold 2 M KOH solution. After the reaction, the concentrations of Cl⁻, ClO⁻ and OH⁻ are respectively (assume volume remains constant)
Given below are two statements : Statement I : The dipole moment of R–CN is greater than R–NC and R–NC can undergo hydrolysis under acidic medium to produce R–COOH. Statement II : R–CN hydrolyses under acidic medium to produce a compound which on treatment with SOCl₂, followed by the addition of NH₃ gives another compound (x). This compound (x) on treatment with NaOCl/NaOH gives a product, that on treatment with CHCl₃/KOH/Δ produces R–NC. In the light of the above statements, choose the correct answer from the options given below.
The wavelength of spectral line obtained in the spectrum of Li²⁺ ion, when the transition takes place between two levels whose sum is 4 and difference is 2, is

Updated for JEE Main 2026: This PYQ is important for JEE Mains, JEE Advanced and other competitive exams. Practice more questions from this chapter.

Scroll to Top