Question

For a dilute solution, mole fraction of solute is given as (n = no. of moles of solute and N = no. of moles of solvent) :

• A. $\frac{n}{N}$
• B. $\frac{N}{n}$
• C. $\frac{N}{n+N}$
• D. Both B and C

Answer 1

The correct option is A $\frac{n}{N}$

$\text{Mole fraction of solute}=\frac{\text{number of moles of solute}}{\text{number of moles of solute}+\text{number of moles of solvent}}$

$=\frac{n}{n+N}$

For a dilute solution,

$n<<N$, therefore we can neglect the term $n$ in the denominator (n+N) $\approx$ N

So,

$\text{Mole fraction of solute}=\frac{n}{N}$

$\therefore$ (A) option is correct.