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)

m, x

Answer 2

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. $m=\frac{\text{weight}\,\text{of}\,\text{solute}}{\text{molecular}\,\text{weight}\,\,\text{ }\\!\\!\times\\!\\!\text{ }\,\text{weight}\,\text{of}\,\text{solvent}}$ and $\underset{\text{(of}\,\text{solute)}}{\mathop{x}}\,=\frac{\omega \text{/}m}{\frac{\omega }{m}+\frac{\omega }{M}}=\frac{\omega M}{\omega M+\omega m}$