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

Define the following terms: Lyophilic colloid

Write the structures of A and B in the following reactions

Write a method by which lyophobic colloids can be coagulated.

Predict the products of the following reactions:

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

Name the reagents used in the following reactions:

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. 

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?

What are enzymes?

Account for the following:

Diazonium salts of aromatic amines are more stable than those of aliphatic amines.

Show how the following compound can be converted to benzoic acid.

Ethylbenzene

Show how the following compound can be converted to benzoic acid.

Acetophenone