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

Why is boiling point of 1 M NaCl solution more than that of 1 M glucose solution?

Assertion (A): Vitamin C cannot be stored in our body.

Reason (R): Vitamin C is fat soluble and is excreted from the body in urine.

The vitamins which can be stored in our body are ______.

Calculate Van't Hoff factor for an aqueous solution of K₃ [Fe(CN)₆] if the degree of dissociation (α) is 0.852. What will be boiling point of this solution if its concentration is 1 molal? (Kb = 0.52 K kg/mol)

What is the reason for the stability of colloidal sols?

Define the following term:

Zeta potential

Define the following terms: Associated colloids

Give reasons for the following observations:

Brownian movement provides stability to the colloidal solution.

Out of MgCl₂ and AlCl₃, which one is more effective in causing coagulation of negatively charged sol and why?

Out of BaCl₂ and KCl, which one is more effective in causing coagulation of a negatively charged colloidal Sol? Give reason.

Give reasons for the following observations: Leather gets hardened after tanning.

Write the structures of the following molecule: 

H₂SO₃

Define the following term : Brownian movement

Draw the structures of the following molecules: H₂S₂O₈

Account for the following : Cl – CH₂COOH is a stronger acid than CH₃COOH.

A group 14 element is to be converted into n-type semiconductor by doping it with a suitable impurity. To which group should this impurity belong?

What is a semiconductor?

Non-stoichiometric cuprous oxide, Cu₂O can be prepared in laboratory. In this oxide, copper to oxygen ratio is slightly less than 2 : 1. Can you account for the fact that this substance is a p-type semiconductor?

Classify each of the following as being either a p-type or a n-type semiconductor:

1. Ge doped with In 
2. B doped with Si