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JEE · NEET Previous Year Question

$The energy of second orbit of hydrogen atom is - 5.45 \times 10^{- 19} J . What is the energy of first orbit of Li^{2 +} ion (in J)?$

Topic: JEE PYQ

Answer: B. Full step-by-step solution below.

A $- 1.962 \times 10^{- 18}$
B $- 1.962 \times 10^{- 17}$
C $- 3.924 \times 10^{- 17}$
D $- 3.924 \times 10^{- 18}$

Correct answer: B

Solution

(b) E_{n} = - 13.6 (\frac{z ^{2}}{n ^{2}}) eV \Rightarrow E_{1} = - 13.6 (\frac{3 ^{2}}{1 ^{2}}) eV = - 122.4 eV = - 122.4 \times 1.602 \times 10^{- 19} J = - 1.962 \times 10^{- 17} J

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