Question

Study the following unbalanced half-reaction. Which equation represents the balanced half-reaction? H2O2 ---> H2O
e- + H+ + 2H2O2 H2O
2e- + 2OH- + H2O 2H2O2
2e- + 2H+ + H2O2 2H2O
3e- + 2H+ + 2HO- 4H2O
4e- + H2O2 2H2O +4e-

Answer 1

O: 1*2 = 2*1 
H 2 + 2 = 2*2 

answer C hope you get it right

Answer 2

Answer : The correct option is, $2e^-+2H^++H_2O_2\rightarrow 2H_2O$

Explanation :

The given unbalanced reaction is,

$H_2O_2\rightarrow H_2O$

(1) The right side is lacking oxygen, so we add a water molecule to it :

$H_2O_2\rightarrow H_2O+H_2O$

or we can write as,

$H_2O_2\rightarrow 2H_2O$

(2) Now we have introduced more hydrogen, so we need to balance hydrogen on the left side in acidic solution, we get

$2H^++H_2O_2\rightarrow 2H_2O$

(3) Now all the atoms are balanced but charge is not balanced. We see that the left side there are two positive charge. So, we balance the charge by adding two negative charge on the left side in the reaction, we get

$2e^-+2H^++H_2O_2\rightarrow 2H_2O$

Therefore, the correct option is, $2e^-+2H^++H_2O_2\rightarrow 2H_2O$