Question

9. The sum of all quantum numbers of the last
electron in Lithium atom is:
(a) 7/2
(b) 2
(c) 5/2
(d) 3​

Answer 1

Answer:

3is the answer

Explanation:

Because the sum in 3

Answer 2

The correct answer is Option C.

Given: Lithium atom.

To Find: Sum of all quantum numbers of the last electron in Lithium atom.

Solution:

Electronic configuration of Li ion is

$1s^{2} 2s^{1}$

Last electron is $2s^{1}$.

k = 2, l = 0, m = 0, s = +$\frac{1}{2}$

The sum of all quantum numbers is

$= 2+0+0+\frac{1}{2} \\ =\frac{5}{2}$

Hence, the answer is option C.

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