Question

''Relative lowering in vapour pressure of solution containing non-volatile solute is directly proportional to mole fraction of solute''. Above statement is :

• A. Henry law
• B. Dulong and Petit law
• C. Raoult's law
• D. Le-Chatelier's principle

Answer 1

Answer: (C)

Raoult's law : For a solution containing non volatile solute at a given temperature is equal to the mole fraction of solute.
$\frac{p_A^{\circ }-p_A}{p_A^{\circ }}=x_B$ (mole fraction of solute)
$p_A^{\circ }=$ vapour pressure of pure solution
$p_A=$ vapour pressure of solution
$x_B=\frac{\text{ moles of solute }}{\text{ moles of solute }+\text{ solvent }}$
Henry law : The solubility of a gas at a given temperature is directly proportional to the pressure at which it is dissolved.
Mole fraction of a gas $\left(x_B\right)\propto P$
Dulong and Petit's law : For any element
Atomic mass $\times$ specific heat $\approx 6.4$
Le-Chatelier's principle : If a system in equilibrium is subjected to a change of concenteration, pressure or temperature, the equilibrium shifts in the direction that tends to undo the effect of the change.