Question

Two binary solutions have the same molarity. Which of the following statements is true?

• A. Equal volumes of the two solutions contain equal number of solute molecules.
• B. Equal weights of the two solutions contain equal number of solute molecules.
• C. The two solutions, must have the same molality.
• D. The two solutions must have the same mole fraction.

Answer 1

Answer: (A)

Molarity $=\frac{w}{M \times V}$

For two solutions having same molarity,

$\frac{w_{1}}{M_{1} \times V_{1}}=\frac{w_{2}}{M_{2} \times V_{2}} $

If $V_{1}=V_{2}, \frac{w_{1}}{M_{1}}=\frac{w_{2}}{M_{2}}$

Thus, solutions contain equal no. of moles of solute and hence equal no. of molecules