The ionization energy of a hydrogen atom is $-13.6 \ eV$. The energy required to excite an electron from the ground state to the first excited state is ...... (Avogadro number = $6.022 \times 10^{23}$)

• A
  $1.69 \times 10^{-20} \ eV$
• B
  $1.69 \times 10^{-23} \ eV$
• C
  $1.69 \times 10^{23} \ eV$
• D
  $1.69 \times 10^{25} \ eV$