Question

Ionisation energy of He+ is

19.6 × 10–18 J atom–1 . The energy of the first stationary state (n = 1) of Li2+is :

• A. 4.41 × 10–16 J atom–1
• B. – 4.41 × 10–17 J atom–1
• C. – 2.2 × 10–15 J atom–1
• D. 8.82 × 10–17 J atom–1

Answer 1

Answer: (B)

– 4.41 × 10–17 J atom–1

Answer 2

I.E. of He+ = 19.6 ´ 10–18 J atom–1

I.E. = – E1

E1 for He+ is = – 19.6 × 10–18 J atom–1

$$$\frac{- 19.6 \times 10^{- 18}}{\left( E_{1} \right)_{LI}2 +} = \frac{4}{9}$ = <img src="https://cdn.pureessence.tech/canvas_311.png?top_left_x=1116&top_left_y=932&width=300&height=278" style="width:0.58333in;height:0.54861in" /> $$E_{1}\left( Li^{2 +} \right) = \frac{- 19.6 \times 9 \times 10^{- 18}}{4}$$ = – 44.1 ´ 10–18 = – 4.41 ´ 10–17 J atom–1