CBSE Class 10 Answered
Electrolysis of Acidified Water
Electrolyte: Acidified water
Electrodes:
Anode: Platinum
Cathode: Platinum
Ionisation of acidified water: H2O → H+ + OH–
H2SO4 → 2H+ + SO42–
Ions present: H+, SO42–, OH–
Electrode reactions:
Reaction at the cathode: H+ + e− → H
H + H → H2 (hydrogen molecule)
Reaction at the anode: OH– − e− → OH × 4
OH– ion discharge in preference to SO42–
4OH → 2H2O + O2 (oxygen molecule)
At the cathode, Hydrogen gas is evolved and at the anode, oxygen gas is liberated.
The water molecule has two atoms of hydrogen and one atom of oxygen, that means in the no. of hydrogens are double than that of oxygen,
hence the amount of hydrogen gas evolved collected in one of the test tubes doubles the amount in the other gas i.e., oxygen.
If the information given in the book you mentioned is not matching with above information then it may considered as a print mistake.