(a) Define the following terms.
(i) Primary batteries
(ii) Corrosion
(b) The resistance of a conductivity cell containing `0.001" M KCl"` solution at 298 K is `1500Omega.` What is the cell constant if conductivity of `0.001" M KCl"` solution at 298 K is `0.146xx10^(-3)Scm^(-1)` ?

Explanation

(a) (i) Primary batteries : Primary batteries the those in which the redox reaction occurs only once and they become dead after something and cannot be used again. Foe example : dry call and mercury cell.
(ii) Corrosion : The process of slowly eating away of the metal due to attack of the atmopheric gases on the surface of the metal resulting into the formation of compounds such as oxides, sulphides, carbonates, sulphates etc., is called corrosion. For example : rusting of iron.
`C=0.001M" "rArr" "R=1500Omega`
`K_(c)=0.146xx10^(-3)Scm^(-1)" "rArr" "K_(c)=((1)/(R))xx((l)/(a))`
`rArr" "K_(c)=(1)/(R)xxG^(**)" "[G^(**)="Cell constant"]`
`G^(**)=0.146xx10^(-3)xx1500`
`=73xx10^(-3)" "rArr" "G^(**)=0.073cm^(-1)`