Question

Ionisation energy for hydrogen atom in the ground state is E. What is the ionisation energy of $Li^{+ +}$ atom in the 2^nd excited state

• A. E
• B. 3E
• C. 6E
• D. 9E

Answer 1

Answer: (A)

E

Answer 2

Ionisation energy of atom in nth state $E_{n} = \frac{Z^{2}}{n^{2}}$

For hydrogen atom in ground state (n = 1) and Z = 1 ⇒

$E = E_{0}$ …..(i)

For $Li^{+ +}$ atom in 2^nd excited state n = 3 and Z = 3, hence $E^{'} = \frac{E_{0}}{3^{2}} \times 3^{2} = E_{0}$ …..(ii)

From equation (i) and (ii) $E^{'} = E$.