Question

The ionisation energy of an electron in the ground state of helium atom is $24.6\, eV$. The energy required to remove both the electron is

• A. 51.8 eV
• B. 79 eV
• C. 38.2 eV
• D. 49.2 eV

Answer 1

Answer: (B)

79 eV

Answer 2

lonisation energy in ground state $=24.6 \,eV$
Energy required to remove $2^{n}$ electron from $He ^{2+}$
$=Z^{2}(13.6)\, eV =(2)^{2}(13.6)=54.4\, eV$
So, total energy required $=24.6+54.4=79\, eV$