Answer
$ 1.1\times 10^{-26}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:
$1\times 10^8\times \Delta E\geq \frac{6.63\times 10^{-34}}{2\pi}$
$\Delta E\geq 1.1\times 10^{-26}J$
