Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

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 ____________.

Semiconductors have conductivity (in ohm^-1 m^-1) in the range of ____________.

The process by which impurity is introduced in semiconductors to enhance its conductivity is known as ____________.

Electrical conductivity of semiconductors increases with increase in ____________.

In which of the pair of ions, both species contain S-S bond?

Which kind of defects are introduced by doping?

Silicon doped with electron-rich impurity forms ______.

Which of the following statements are true about semiconductors?

(i) Silicon doped with electron-rich impurity is a p-type semiconductor.

(ii) Silicon doped with an electron-rich impurity is an n-type semiconductor.

(iii) Delocalised electrons increase the conductivity of doped silicon.

(iv) An electron vacancy increases the conductivity of n-type semiconductor.

Why are solids incompressible?

Why does the electrical conductivity of semiconductors increase with rise in temperature?

Assertion: Semiconductors are solids with conductivities in the intermediate range from 10^–6 – 10⁴ ohm^–1m^–1.
Reason: Intermediate conductivity in semiconductor is due to partially filled valence band.

Which of the following will show Tyndall effect?

The values of colligative properties of colloidal solution are of small order in comparison to those shown by true solutions of same concentration because of colloidal particles ______.

Which of the following statements are correct?

(i) Mixing two oppositely charged sols neutralises their charges and stabilises the colloid.

(ii) Presence of equal and similar charges on colloidal particles provides stability to the colloids.

(iii) Any amount of dispersed liquid can be added to emulsion without destabilising it.

(iv) Brownian movement stabilises sols.