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(ii) 1.0MNa₂SO₄

(i) A–B interactions are stronger than those between A–A or B–B.

(1) Colligative Property : The property of a solution which depends on the total number of particles of the solute (molecules, ions) present in the solution and does not depend on the nature or chemical composition of solute particles is called colligative property of the solution.

(2) Examples of colligative properties : 

(a) lowering or relative lowering of vapour pressure of a solution 

(b) elevation in the boiling point 

(c) depression in the freezing point 

(d) osmotic pressure.

(1) Relative vapour pressure of a solution : If P₀ is the vapour pressure of a pure liquid (solvent) and P is the vapour pressure of a solution after adding a nonvolatile solute, then, relative vapour pressure = \(\frac{P}{P_0}\).

(2) Lowering of vapour pressure of a solution : When a nonvolatile solute is added to a pure solvent, the surface area is covered by the solute molecule decreasing the rate of evaporation, hence its vapour pressure decreases. This decrease in vapour pressure is called lowering of vapour pressure. If P₀ is the vapour pressure of a pure solvent (liquid) and P is the vapour pressure of the solution, where P < P₀, then, (P₀ – P) is the lowering of the vapour pressure.

(3) Relative lowering of vapour pressure : If P₀ and P are the respective vapour pressures of a pure liquid (solvent) and the solution containing a non-volatile solute then P < P₀. 

Hence, 

P₀ – P represents the lowering of the vapour pressure due to addition of a nonvolatile solute.

∴ Relative lowering of vapour pressure = \(\frac{P_0-P}{P_0}\) = \(\frac{ΔP}{P_0}\)

1. The pure water moves through the semipermeable membrane to the NaCl solution due to osmosis.

2. This process can be reversed by applying pressure greater than the osmotic pressure to the solution side. Now the pure water moves from the solution side to the solvent side and this process is called reverse osmosis.

3. Reverse osmosis can be defined as a process in which a solvent passes through a semipermeable membrane in the opposite direction of osmosis, when subjected to a hydrostatic pressure greater than the osmotic pressure.

The degree of dissociation α is equal to \(\frac{i-1}{n-1}\).

1. Two solutions having same osmotic pressure at a given temperature are called isotonic solutions. 

2. When such solutions arc separated by a semipermeable membrane, solvent flow between one to the other on either direction is same. 

i.e., the net solvent flow between two isotonic solutions is zero.

1. Saturated solution: When maximum amount of solute is dissolved in a solvent, any more addition of solute will result in precipitation at a given temperature and pressure. Such a solution is called a saturated solution.

2. Unsaturated solution: When minimum amount of solute is dissolved in a solvent at a given temperature and pressure is called an unsaturated solution.

3. Super saturated solution: It is a solution that holds more solute than it normally could in its saturated form.

Example: 

1. A saturated solution where the addition of more compound would not dissolve in the solution. 359 g of NaCI in 1 liter of water at 25°C.

2. An unsaturated solution has the capacity to dissolve more of the compound. 36 g of NaCI in 1 litre of water at 25°C.

3. A super saturated solution is the solution in which crystals can start growing. 500 g of NaCI in 1 liter of water at 25°C.

C = 0.25 M 

T = 370.28 K 

(π)_glucose = CRT 

(π) = (0.25 mol L^-1) x (0.082 L atm K^-1 morl^-1) x (370.28 K) 

= 7.59 atm

Number of moles of the solute dissolved per dm³ of solution is molarity.

1. A solution is a homogeneous mixture of two or more substances consisting of atoms. ions or molecules. 

2. For example, when a small amount of NaCl is dissolved in water, a homogeneous solution is obtained. In this solution, Na⁺ and C^- ions are uniformly distributed in water. Here NaCI is the solute and water is the solvent.

1. If the solute is dissolved in the solvent water, the resultant solution is called as an aqueous solution. 

Example, salt in water. 

2. If the solute is dissolved in the solvent other than water such as benzene, ether, CCl₄ etc, the resultant solution is called a non aqueous solution. 

Example, Br, in CCI₄.

Osmotic pressure can be defined as the pressure that must be applied to the solution to stop the influx of the solvent (to stop osmosis) through the semipermeable membrane.

Henry’s law: 

This law states “that the partial pressure of the gas in vapour phase is directly proportional to the mole fraction (x) of the gaseous solute in the solution at low concentrations.”

P_solute ∝ x_{solute in solution} 

P_solute = K_H . x_{solute in soluation} 

x_solute = mole fraction of solute in the solution 

K_H = empirical constant. 

P_solute = Vapour pressure of the solute (or) the partial pressure of the gas in vapour state. The value of K_H depends on the nature of the gaseous solute and solvent.

When NaCl is dissolved in water, boiling point  increases.

1. Henry’s law is applicable at moderate temperature and pressure only. 

2. Only the less soLuble gases obey Henry’s law.

3. The gases reacting with solvent do not obey Henry’s law. 

4. The gases obeying Henrys law should not associated or dissociated while dissolving in the solvent.

Formality (F) is defined as the number of formula weight of solute present in 1 litre of the solution.

Formality (F) = (Number of formula weight of solute) / (Volume of the solution (1 L))

1. The solubility of oxygen gas decreases with the increase in temperature. 

2. In sea or lake water, the temperature of upper level is higher than the lower level.

3. Therefore the dissolved oxygen content in water is more at lower level than at higher level required for the marine life.

Hence marine life like fish prefers to stay at lower level than upper level of water.

Л = i x C x R x T

2.5 = i x ( 3/246) x ( 0.0821 / 0.1) x 298

i = 2.01

As i > 1 the solute A undergoes dissociation.

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The net vapour pressure of the solution decreases because newly formed hydrogen bonds are stronger forces of attraction than the original forces of attraction existing in separate solutions.

Binary solution is a solution containing only one solute dissolved in a solvent.

The number of moles of solute dissolved in one litre or 1dm³ of solution is known as molarity.