ISC (Science) ISC Class 12 - CISCE Important Questions for Chemistry (Theory)

In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes?

Why do gases always tend to be less soluble in liquids as the temperature is raised?

State Raoult’s law for the solution containing volatile components

The solubility product (K_sp) of BaSO₄ is 1.5 X 10^-9.Calculate the solubility of barium sulphate in pure water and in 0.1 M BaCl₂.

Fill in the blanks by choosing the appropriate word/words from those given in the brackets: 

Ideal solutions obey ………. law and they …………. form azeotropic mixtures.

(Henry’s, aldol condensation, absence, do not, ohm, Raoult’s, increases, common ion effect, easily, three, solubility product, ohm^-1, two, four, ohm^-1, cm², Cannizzaro, ohm^-1 cm^-1, zero, decreases, presence)

The solubility product of PbCl₂ at 298K is 1.7 × 10^-5. Calculate the solubility of PbCl₂ in g/lit. at 298K. 
Atomic Weights: [Pb = 207 and Cl = 35.5]

For the reaction :

\[\ce{2NO_{(g)} ⇌ N2_{(g)} + O2_{(g)}}\];

ΔH = -heat

K_c = 2.5 × 10² at 298K

What will happen to the concentration of N₂ if :

(1) Temperature is decreased to 273 K.

(2) The pressure is reduced

Match the following:

A solution containing 8.44 g of sucrose in 100 g of water has a vapour pressure 4.56 mm of Hg at 273 K. If the vapour pressure of pure water is 4.58 mm of Hg at the same temperature, calculate the molecular weight of sucrose. 

Define Raoult’s law for the elevation of the boiling point of a solution.

What will be the vapour pressure of a solution containing 5 moles of sucrose (C₁₂H₂₂O₁₁) in 1 kg of water, if the vapour pressure of pure water is 4.57 mm of Hg? [C = 12, H = 1, O = 16]

A solution is prepared by dissolving 9.25 g of non-volatile solute in 450 mL of water. It has an osmotic pressure of 350 mm of Hg at 27°C. Assuming the solute is non-electrolyte, determine its molecular mass. (R = 0.0821 lit atm K^-1 mol^-1)

Define the following term with suitable examples:

Peptisation

Define the following term with suitable examples:

Electrophoresis.

An aqueous solution of urea freezes at – 0.186°C, K_f for water = 1.86 K kg mo1^–1, K_b for water = 0.512 K kg mo1^–1. The boiling point of urea solution will be:

Calculate the osmotic pressure of a solution prepared by dissolving 0.025 g of K₂SO₄ in 2.0 litres of water at 25°C assuming that K₂SO₄ is completely dissociated. (Mol. wt. of K₂SO₄ = 174 g mol^–1)

The molal freezing point constant of water is 1·86 K kg mol^-1. Therefore, the freezing point of 0·1 M NaCl solution in water is expected to be:

1) -1.86°C

2) -0.372 °C

3) -0.186 °C

4) +0.372 °C

If 1·71 g of sugar (molar mass = 342) are dissolved in 500 ml of an aqueous solution at 300 K, what will be its osmotic pressure?

0·70g of an organic compound, when dissolved in 32g of acetone, produces an elevation of 0·25°C in the boiling point. Calculate the molecular mass of the organic compound (K_b for acetone = 1·72 K kg `mol^(-1)`).

 Fill in the blanks by choosing the appropriate word/words from those given in the brackets: 
(more than, primary, cathode, Lucas reagent, two, four, less than, Grignard’s reagent, tertiary anode, zero, equal to, three)
 The elevation of boiling point of 0.5 M K2SO4 solution is ________ that of 0.5 M urea solution. The elevation of boiling point of 0.5 M KCl solution is _______ that of 0·5 M K2SO4 solution.