If a substance 'A' dissolves in solution of a mixture of ' B ' and ' C ' with their respective number of moles as $\mathrm{n}_{\mathrm{A}}, \mathrm{n}_{\mathrm{B}}$ and $\mathrm{n}_{\mathrm{C}}$, mole fraction of C in the solution is:

(B) $\frac{n_{C}}{n_{A}+n_{B}+n_{C}}$

(A) $\frac{n_{C}}{n_{A} \times n_{B} \times n_{C}}$

(D) $\frac{n_{B}}{n_{A}+n_{B}}$

JEE Main · 2024 · 30 Jan 2024 · Shift 2 · Some Basic Concepts of Chemistry

If a substance 'A' dissolves in solution of a mixture of ' B ' and ' C ' with their respective number of moles as

n_{A}, n_{B}

and

n_{C}

, mole fraction of C in the solution is:

(A) $\frac{n _{C}}{n _{A} \times n _{B} \times n _{C}}$
(B) $\frac{n _{C}}{n _{A} + n _{B} + n _{C}}$ ✓ Correct
(C) $\frac{n _{C}}{n _{A} - n _{B} - n _{C}}$
(D) $\frac{n _{B}}{n _{A} + n _{B}}$

Answer: (B)

Solution

Mole fraction of any component in a solution is that component's moles divided by the total moles of all components present. For substance A dissolved in a mixture of B and C, present as

n_{A}

n_{B}

n_{C}

moles, the mole fraction of C is

χ_{C} = \frac{n _{C}}{n _{A} + n _{B} + n _{C}}

JEE Main · 2024 · 30 Jan 2024 · Shift 2 · Single correct option

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