In electrolysis of water : 1.name the gas collected at the cathode and anode respectively? 2.how we will test this evolved gas ?

1.

Hydrogen and oxygen respectively.

2.

Hydrogen will burn with a " squeaky pop" when treated with a burning splint. Oxygen re-lights a glowing splint.

At the cathode (-) water is reduced:

##H_2O_((l))+erarr1/2H_(2(g))+OH_((aq))^-##.

At the anode (+) water is oxidized:

##H_2O_((l))rarr1/2O_(2(g))+2H_((aq))^(+)+2e##