Online Test: Solutions | Class 12 Chemistry

Question 1 of 20

Molarity is defined as moles of solute per:

kg of solvent

litre of solution

litre of solvent

kg of solution

Explanation: Molarity $M=n/V$ uses litres of solution.

Question 2 of 20

Which concentration term is temperature-dependent?

Mole fraction

Molality

Molarity

Mass percentage

Explanation: Volume changes with temperature, so molarity varies.

Question 3 of 20

Henry's law is expressed as:

$p=K_H/x$

$p=K_H x$

$x=K_H p^2$

$p=x/K_H$

Explanation: Partial pressure is proportional to mole fraction: $p=K_H x$.

Question 4 of 20

Solubility of a gas in a liquid generally:

increases with temperature

decreases with pressure

decreases with temperature

is independent of pressure

Explanation: Gas dissolution is exothermic, so higher temperature lowers solubility.

Question 5 of 20

For an ideal solution, $\Delta_{mix}H$ and $\Delta_{mix}V$ are:

both positive

both negative

both zero

positive and negative respectively

Explanation: Ideal solutions show no enthalpy or volume change on mixing.

Question 6 of 20

Ethanol + water is an example of:

ideal solution

positive deviation

negative deviation

maximum-boiling azeotrope only

Explanation: Weaker A–B interactions give higher-than-ideal vapour pressure (positive deviation).

Question 7 of 20

Acetone + chloroform shows negative deviation because:

A–B forces are weaker

hydrogen bonding strengthens A–B forces

there is no interaction

both are non-polar

Explanation: Hydrogen bonding between unlike molecules lowers vapour pressure.

Question 8 of 20

A minimum-boiling azeotrope is associated with:

large negative deviation

ideal behaviour

large positive deviation

zero deviation

Explanation: Positive deviation produces a vapour-pressure maximum, hence a boiling-point minimum.

Question 9 of 20

The relative lowering of vapour pressure equals the:

mole fraction of solvent

mole fraction of solute

molality

molarity

Explanation: $(p^0-p)/p^0=x_{solute}$.

Question 10 of 20

Which of the following is NOT a colligative property?

Osmotic pressure

Boiling point of pure water

Depression of freezing point

Relative lowering of vapour pressure

Explanation: Colligative properties relate to the solution, not the pure solvent's boiling point.

Question 11 of 20

The elevation of boiling point is given by:

$\Delta T_b=K_f m$

$\Delta T_b=K_b m$

$\Delta T_b=CRT$

$\Delta T_b=p^0 x$

Explanation: $\Delta T_b=K_b m$ where $K_b$ is the ebullioscopic constant.

Question 12 of 20

Ethylene glycol is added to car radiators to:

raise vapour pressure

depress the freezing point

increase density only

speed up boiling

Explanation: It depresses the freezing point, preventing the coolant from freezing.

Question 13 of 20

Osmotic pressure $\Pi$ for a dilute solution equals:

$K_b m$

$CRT$

$K_f m$

$x p^0$

Explanation: $\Pi=CRT$ with $C$ the molar concentration.

Question 14 of 20

Two solutions with the same osmotic pressure are called:

hypertonic

hypotonic

isotonic

saturated

Explanation: Equal osmotic pressure means the solutions are isotonic.

Question 15 of 20

For NaCl dissolving completely in water, the van't Hoff factor is about:

0.5

1

2

3

Explanation: NaCl gives 2 ions, so $i\approx2$.

Question 16 of 20

A van't Hoff factor less than 1 indicates:

dissociation

no change

association

ionisation

Explanation: Association reduces particle count, giving $i<1$ (e.g. benzoic acid in benzene).

Question 17 of 20

Osmotic pressure is preferred for molar mass of macromolecules because:

it is temperature-independent

it gives measurable values at low concentration

it needs no membrane

it equals molality

Explanation: Even dilute protein solutions give measurable osmotic pressures at room temperature.

Question 18 of 20

The degree of dissociation is $\alpha=$

$\frac{i-1}{n-1}$

$\frac{n-1}{i-1}$

$i(n-1)$

$\frac{1}{i}$

Explanation: $\alpha=\frac{i-1}{n-1}$ for a solute dissociating into $n$ particles.

Question 19 of 20

Molality of a solution containing 1 mol solute in 2 kg solvent is:

0.5 m

1 m

2 m

0.25 m

Explanation: $m=1/2=0.5\ \text{mol kg}^{-1}$.

Question 20 of 20

A larger Henry's constant $K_H$ corresponds to:

a more soluble gas

a less soluble gas

no change in solubility

a solid solute

Explanation: Since $x=p/K_H$, a larger $K_H$ gives lower solubility.

Online Test — Solutions