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

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

Explain the following with suitable examples:

12-16 group compounds

What modification can you suggest in the Hardy-Schulze law?

Explain what is observed when a beam of light is passed through a colloidal sol.

Explain what is observed when an electrolyte NaCl is added to hydrated ferric oxide sol.

Explain what is observed when an electric current is passed through a colloidal sol?

Explain the term Electrophoresis

Explain the terms Coagulation

Explain the terms Dialysis 

Explain the term Tyndall effect.

What happens when sulphur dioxide is passed through an aqueous solution of Fe(III) salt?

What happens when a freshly prepared precipitate of Fe(OH)₃ is shaken with a small amount of FeCl₃ solution?

What happens when persistent dialysis of a colloidal solution is carried out?

What happens when an emulsion is centrifuged?

Account for the following :

H₃PO₂ is a stronger reducing agent than H₃PO₃.

 Draw structures of the following: 
`S_2O_8^{2-}`