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
<h3>What is Spin Quantum Number ?</h3>
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:
- Principal quantum number (n) which cannot be zero.
The allowed values of n are therefore 1, 2, 3, 4, and so on.
- Angular quantum number (l) is able to be any integer between 0
and n-1.
Therefore, for example, If n = 1, l will be 0,
If n = 2, l can be either 0 or 1.
- Magnetic quantum number (m) is able to be any integer between -l and +l.
Therefore, for example, If l = 3, m can be either -3 to +3.
- Spin Quantum Number (ms): Ms = +½ or -½ accounts for the orientation of the spin axis of an electron as it is able to spin in only one of two directions.
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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