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

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?

Account for the following:

pK_a value of 4-nitrobenzoic acid is lower than that of benzoic acid.

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?

Why are alkyl halides insoluble in water?

Account for the following :

H₃PO₂ is a stronger reducing agent than H₃PO₃.

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

What type of semiconductor is obtained when 
Ge is doped with In?

 What type of semiconductor is obtained when 
 Si is doped with P? 

Write one difference between transition elements and p-block elements with reference to variability of oxidation states.

Answer the following question.
Why are medicines more effective in the colloidal state?

A colloidal sol is prepared by the given method in the figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the solution represented? 

A colloidal sol is prepared by the given method in the figure. What is the charge on hydrated ferric oxide colloidal particles formed in the test tube? How is the sol represented?

Solids with conductivities ranging from 10⁴ to 10⁷ ohm^-1 m^-1 are ____________.