Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Mention three areas in which H₂SO₄ plays an important role.

Why is `K_(a_2) "<<" K_(a_1)` for `H_2SO_4` in water?

Describe the manufacture of H₂SO₄ by contact process?

Write balanced equations for NaCl is heated with sulphuric acid in the presence of MnO₂

Give reasons : Silicon on doping with Phosphorous forms n-type semiconductor.

Write the reactions involved Hell-Volhard Zelinsky reaction?

When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was evolved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas (A) changed into a colourless solid (B).

1) Identify (A) and (B).

2) Write the structures of (A) and (B).

3) Why does gas (A) change to solid on cooling?

 Write the name of the vitamin whose deficiency causes bleeding of gums.

Illustrate the following reactions giving suitable example in each case 

Coupling reaction

Give one example each of 'oil in water' and 'water in oil' emulsion.

Account for the following:

Carboxylic acid is a stronger acid than phenol.

 Complete and balance the following equations: 
S+H₂SO₄(conc.)  → 

What happens when Salicylic acid is treated with (CH₃CO)₂ O/H⁺?

 Arrange the following compounds in increasing order of their property as indicated:
 F - CH₂COOH, O₂N - CH₂ COOH CH₃ COOH,HCOOH - acid character. 

Answer the following question.
What is the difference between an emulsion and a gel?

Write equations of the following reactions:
Coupling reaction

A group of 14 elements is converted into n-type semiconductor by doping it with:

Group 14 element is converted to p-type semiconductor by doping it with:

In n-type semiconductor, current is carried by ____________.

Which transition metal oxide has appearance and conductivity like that of copper?