Answer Q no. 10 (c,d)           

(c) During the electrolysis of an aqueous solution of NaCl, hydrogen ion is reduced at the cathode and not sodium ion though both Na⁺ and H⁺ ions are present in the solution.
(d) On electrolysis of diluted at the cathode but no hydrogen gas evolves there, Explain why?                 

Dear Student,

Ans,10.c)

• Electrolysis of aqueous NaCl: 

Here, NaCl and Water H₂O both are present and both dissociate as

NaCl -----------> Na⁺ + Cl^-

H₂O--------------> H⁺ + OH^-

Reaction as cathode: Both Na⁺ and H⁺ will compete for cathode but reaction with higher E⁰ is preferred

 Na⁺ + e^- ----------> Na  E⁰ = -2.71 V  (1)

H⁺+ e^- -----------> 1/2 H₂   E⁰ = 0.00 V  (2)

Since, (2) has higher value of E⁰ So, H₂ is product deposited at cathode. 

Note-The eqn 2 can also be written as  H₂O + e^- --------------> 1/2 H₂ + OH^-

Hence, Hydrogen ion is reduced at the cathode, and not the Sodium ion.

P.S. kindly post separate questions in separate threads.

Regards