Discussion Forum



1)

Ionisation energy of He+ is 19.6 x 10-18 J atom-1. The energy of the first stationary state (n = 1) of Li2+ is


A) 4.4×10−16Jatom−1

B) −4.4×10−17Jatom−1

C) −2.2×10−15Jatom−1

D) 8.82×10−17Jatom−1

Answer:

Option B

Explanation:

I.E=Z2n2×13.6eV  ....(i)

I1I2=Z21n21×n22Z22 ...(ii)

Given I1 = -19.6 x 10-18 Z1 = 2, n1= 1, Z2 = 3 and n2 = 1

Substituting these values in equation (ii).

−19.6×10−18I2=41×19

Or I2 = -19.6×10−18×94 = −4.4×10−17Jatom−1