Let \(x\) be the amount of \(12\%\) sodium hypochlorite solution needed.

Amount of sodium hypochlorite in \(x\) litres of \(12\%\) solution $$\=>(12/100)\times x$$

And the required volume of \(2\) liters is \(100\), so the volume of \(12\%\) solution in \(100\) liters of \(2\%\) solution is $$=(2/100)\times 100=2$$

Now $$(12/100)X=2$$ $$=>x=(2\times 100)/12=50/3=16.67\text{ Litres}$$