Question

Mole fraction of the solute in a 1.00 molal aqueous solution is :

• A. $1.7700$
• B. $0.1770$
• C. $0.0177$
• D. $0.0344$

Answer 1

The correct option is C $0.0177$

$1$ molal aqueous solution means

$1$ mole of solute is dissolved in $1kg$ of water

$\Rightarrow$ No. of moles of solute=$1$ mole

No. of Moles of water=$\frac{1000}{18g/mole}=55.55$ moles

$\therefore$ Total no. of moles=$1+55.55=56.55$ moles

Now, we know

Mole fraction of solute=$\frac{Molesofsolute}{Totalmolesinsolution}$

$\Rightarrow$ Mole fraction in solute=$\frac{1}{56.55}=0.0177$