Which problem is already balanced? 2Na+2H_(2)Oarrow 2NaOH+H_(2) PbO_(2)+2H_(2)-gt H_(2)SO_(4) NaOH+3AgNO_(3)-gt 3AgOH+NaNO_(3) SO_(2)+H_(2)Oarrow H_(2)SO_(4)

The balanced chemical equation is:<br /><br />$2Na+2H_{2}O\rightarrow 2NaOH+H_{2}$<br /><br />In this equation, the number of atoms of each element is the same on both sides of the equation, which means it is balanced.