What is 2 H2 + 1 O2 = 2 H2O balanced?

Yes, that is correctly balanced. 2 H2 + 1 O2 = 2 H2O is already balanced.

Explanation:

If you count up the number of hydrogen atoms and oxygen atoms on each side, you will see that they are equal:

2 H2 + 1 O2 (4 hydrogen and 2 oxygen) = 2 H2O (4 hydrogen and 2 oxygen).

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.