In the REDOX reaction in basic solution

Zn-->Zn(OH)4+H2
I know that the first half reaction is
4H20+Zn-->Zn(OH)4 +4H+e

but the second one
is either
2e+2H2O--->H2+2OH
(WHICH IS THE ANSWER GIVEN ON THE WORKSHEET)
OR
2e+2H-->H2
I think both leads to the same answer=

2OH+Zn+2H20-->Zn(OH)4 +H2
but I'm not sure if I should add OH instead of H protons since it is a reaction in basic solution.
Someone can help me?

What is the redox equation you are trying to find the half reactions for?

Your entire question is confusing because of the "it might be this, but" and "or it might be this, but..."
If you can clean up the question I can help.
The correct final equation, which you have written as the last step is correct (if you put the charges on).
2H2O + Zn + 2OH^- ==>Zn(OH)4^-2 + H2
In that total redox equation, one half cell is
Zn ==> Zn^+2 + 2e and the other is
2OH^- + 2e + 2H2O ==> H2 + 4OH^-

my question is about whether I have to add water or just H to firstly balance the second half reaction

either
2e+2H2O--->H2+2OH

OR
2e+2H-->H2
which one is correct for a basic solution reaction ?
thanks a lot

Oh I see you answered that, So , it is incorrect to add 2H to balance H2 in a basic solution... ?

Although all the first steps are the same as used in acidic solution?

In basic solution you add OH^- and not H^+. Either will work; e.g., if adding H^+, then you balance the H^+ added with OH^- and it all comes out in the wash.

However, answer on the worksheet or not, I don't buy that the half cell is
2e + 2H2O ==> H2 + 2OH^-

You didn't say what redox equation you are trying to balance. This one comes from
Zn + OH^- --> Zn(OH)4^-2 + H2 and the two half cells are
Zn ==> Zn^+2 + 2e and
OH^- + ....etc.

The point I'm trying to make is that the H2 gas comes from the base (the OH^- in the initial equation) and not from the H2O which is added as a result of the reaction.

thanks a lot

the original question was Zn ==> Zn(OH)4^-2 + H2

In a REDOX reaction in basic solution, it is important to ensure that the number of electrons and the number of atoms of each element is balanced in both the half-reactions. Additionally, you are correct in considering the presence of OH- ions in the basic solution.

Let's break down the reaction step by step:

1. First half-reaction:
4H2O + Zn --> Zn(OH)4 + 4H+ + e-
To balance this half-reaction, we start by balancing the atoms other than oxygen and hydrogen. In this case, Zn is already balanced. Next, balance the oxygen atoms by adding H2O molecules to the side that has fewer oxygen atoms. Adding 4 H2O to the left-hand side balances the oxygen atoms:

4H2O + Zn --> Zn(OH)4 + 4H+ + e-
Now, balance the hydrogen atoms by adding H+ ions to the side that has fewer hydrogen atoms. Adding 4H+ to the left-hand side balances the hydrogen atoms:

4H2O + Zn --> Zn(OH)4 + 4H+ + e-
Finally, balance the charge by adding an electron to the right-hand side:

4H2O + Zn --> Zn(OH)4 + 4H+ + e-

2. Second half-reaction:
Now, let's consider the second half-reaction. The two options you provided are:
a) 2e- + 2H2O --> H2 + 2OH-
b) 2e- + 2H+ --> H2

In a basic solution, we typically use OH- ions instead of H+ ions. Therefore, the correct option for the second half-reaction is the one that includes OH- ions:
2e- + 2H2O --> H2 + 2OH-

3. Balanced overall reaction:
Now that we have both half-reactions, we can combine them to obtain the balanced overall reaction. To do so, we make sure the number of electrons cancels out when adding the half-reactions:

Multiply the first half-reaction by 2:

8H2O + 2Zn --> 2Zn(OH)4 + 8H+ + 2e-

Now, both half-reactions have 2 electrons. Add the two reactions together, making sure all the terms cancel out:

8H2O + 2Zn + 2e- + 2e- --> 2Zn(OH)4 + 8H+ + 2OH-
Simplifying:

8H2O + 2Zn + 4e- --> 2Zn(OH)4 + 8H+ + 2OH-

Finally, we can combine the OHand H+ ions to form water (H2O):

8H2O + 2Zn + 4e- --> 2Zn(OH)4 + 8H2O + 2H2O
Simplifying:

10H2O + 2Zn + 4e- --> 2Zn(OH)4 + 2H2O

Canceling out the water molecules:

10H2O + 2Zn + 4e- --> 2Zn(OH)4

Therefore, the balanced overall reaction in basic solution is 10H2O + 2Zn + 4e- --> 2Zn(OH)4.