Chemistry - Concentration Terms Question with Solution | TestHub

Question Explanation: Find molality.

Concept: This question is based on interconversion of concentration terms.

Solution:

$$\text{ molality }=\frac{\text{ mole of solute }}{\text{ mass of solvent }(\mathrm{kg})}$$

mass of solution $=\mathrm{d}\times \mathrm{v}$

$$=1\times 1000=1000\mathrm{g}=1\mathrm{kg}$$

mass of solvent $=1000-200=800\mathrm{g}$

$$\text{ molality }=\frac{200}{200}\times \frac{1000}{(1000-200)}=1.25\mathrm{m}$$

Final Answer: Option (B)