Question

Out of molality (m), molarity (M), formality (F), normality (N) and mole-fraction (x), the two quantities, independent of temperature, are:

• A. N, m
• B. m, x
• C. m, N
• D. F, N

Answer 1

Answer: (B)

Molality (m) and mole-fraction (x) are independent of volume of solution, hence, also independent of the temperature. Their formula is based on only weights. $m=\frac{\text{weight}\text{of}\text{solute}}{\text{molecular}\text{weight}\times \text{weight}\text{of}\text{solvent}}$ and $\underset{\text{(of}\text{solute)}}{x}=\frac{\omega \text{/}m}{\frac{\omega }{m}+\frac{\omega }{M}}=\frac{\omega M}{\omega M+\omega m}$