The forth quantum number is Spin quantum number and the value of Spin Quantum Number of 1s² will be +1/2. Therefore, the correct option is (B) option
It describes the orientation of the electron spin (rotation) in space.
In the given case of 1s² configuration,
since, the Quantum numbers are known as:
The allowed values of n are therefore 1, 2, 3, 4, and so on.
and n-1.
Therefore, for example, If n = 1, l will be 0,
If n = 2, l can be either 0 or 1.
Therefore, for example, If l = 3, m can be either -3 to +3.
Thus, since the fourth quantum number is Ms, spin, we infer that the answer is (B) option ie, Ms = +1/2 because it represents the positive spin on 1s².
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