An electron is trapped in a deep well with a width of $0\mathrm{.}3$ nm $.$ If it is in the state with quantum number $n=3$ its kinetic energy is:

$6\mathrm{.}0{10}^{-28}J$

$1\mathrm{.}8{10}^{-27}J$

$6\mathrm{.}7{10}^{-19}J$

$2\mathrm{.}0{10}^{-18}J$

$6\mathrm{.}0{10}^{-18}J$