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

Write a method by which lyophobic colloids can be coagulated.

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

Why vitamin C cannot be stored in our body?

3.9 g of benzoic acid dissolved in 49 g of benzene shows a depression in freezing point of 1.62 K. Calculate the van't Hoff factor and predict the nature of solute (associated or dissociated).

(Given : Molar mass of benzoic acid = 122 g mol⁻¹, K_f for benzene = 4.9 K kg mol⁻¹)

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

Predict the products of the following reactions :

Define the following term:

Multimolecular colloids

Calculate the amount of benzoic acid (C₆H₅COOH) required for preparing 250 mL of 0.15 M solution in methanol.

19.5 g of CH₂FCOOH is dissolved in 500 g of water. The depression in the freezing point of water observed is 1.0°C. Calculate the van’t Hoff factor and dissociation constant of fluoroacetic acid.

How are the colloidal solutions classified on the basis of physical states of the dispersed phase and dispersion medium?

Why are hydrophobic sols easily coagulated?

How are colloids classified on the basis of Physical states of components

How are colloids classified on the basis of the nature of the dispersion medium?

How are colloids classified on the basis of interaction between the dispersed phase and the dispersion medium?

How are vitamins classified? Name the vitamin responsible for the coagulation of blood.

Why are vitamin A and vitamin C essential to us? Give their important sources.

How will you bring about the following conversion in not more than two steps?

Benzoic acid to Benzaldehyde

Describe the following:

Decarboxylation

Comment on the nature of two S−O bonds formed in SO₂ molecule. Are the two S−O bonds in this molecule equal?

How is the presence of SO₂ detected?