Answer
$4.22\times 10^{-25}J$
Work Step by Step
According to Heisenberg's principle
$\Delta E.\Delta t\geq\frac{h}{2\pi}$
We plug in the known values to obtain:
$2.5\times 10^{-10}\times \Delta E\geq\frac{6.63\times 10^{-34}}{2\pi}$
$\implies 2.5\times 10^{-10}\times \Delta E\geq 1.055\times 10^{-34}$
$\Delta E\geq 4.22\times 10^{-25}J$