Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

Indicate the σ and π bond in the following molecule:

HCONHCH₃

Aqueous copper sulphate solution (blue in colour) gives a bright green solution with aqueous potassium chloride. Explain this experimental result.

Explain the violet colour of the complex [Ti(H₂O)₆]³⁺ on the basis of crystal field theory.

Give the uses of DDT.

Give the uses of carbon tetrachloride.

Give the uses of iodoform.

What are lyophilic and lyophobic colloids ? Which of these sols can be easily coagulated on the addition of small amounts of electrolytes?

Define the following terms: Lyophilic colloid

Write a method by which lyophobic colloids can be coagulated.

Calculate the amount of CaCl₂ (molar mass = 111 g mol⁻¹) which must be added to 500 g of water to lower its freezing point by 2 K, assuming CaCl₂ is completely dissociated. (K_f for water = 1.86 K kg mol⁻¹)

Complete the equation

PbS + O₃ ⟶

Out of sulphur sol and proteins, which one form multimolecular colloids?

Account for the following :

Ozone is thermodynamically unstable.

Calculate the freezing point of solution when 1.9 g of MgCl₂ (M = 95 g mol⁻¹) was dissolved in 50 g of water, assuming MgCl₂ undergoes complete ionization.

(K_f for water = 1.86 K kg mol⁻¹)

When 2.56 g of sulphur was dissolved in 100 g of CS₂, the freezing point lowered by 0.383 K. Calculate the formula of sulphur (S_x).

(K_f for CS₂ = 3.83 K kg mol⁻¹, Atomic mass of sulphur = 32 g mol⁻¹]

Give reasons for the following observations: Lyophilic sol is more stable than lyophobic sol. 

Give reasons : Racemic mixture is optically inactive.

How the supersonic jet aeroplanes are responsible for the depletion of ozone layers?

Calculate the freezing point of the solution when 31 g of ethylene glycol (C₂H₆O₂) is dissolved in 500 g of water.

(K_f for water = 1.86 K kg mol^–1)

Define the following term:

Multimolecular colloids