The semiconductor whose increased conductivity is a result of negatively-charged electrons is called an n-type semiconductor. These are generated when the crystal of a group 14 element such as Si or Ge is doped with a group 15 element such as P or As.

Peptization can be defined as a process of converting a precipitate into colloidal sol by shaking it with dispersion medium in the presence of small amount of electrolyte.The electrolyte used in this process is known as a peptizing agent.

Copper can be obtained from low grade from low through the process of leaching using acid or bacteria (leaching processes in which ore is treated with a suitable reagent which dissolves ore but not the impurities). 

Basicity of H₃PO₂ depends on upon the number of ionizable -OH groups present in the molecule. That is the number of hydrogen attached to the electronegative atom oxygen.

H₃PO₂ has one ionizable –OH group, thus its basicity is 1.

 The structure of H₃PO₂ is as follows:

Let the concentration of the reactant be [A] = a

Rate of reaction, R = k [A]² = ka²

(i) If the concentration of the reactant is doubled, i.e. [A] = 2a, then the rate of the reaction would be

R = k (2a)²

= 4ka

= 4R

Therefore, the rate of the reaction would increase by 4 times.

(ii) If the concentration of the reactant is reduced to half, i.e.,  then the rate of the reaction would be

Therefore, the rate of the reaction would be reduced to