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Question
State and explain Pauli's exclusion principle.
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Solution
Pauli’s exclusion principle states that “No two electrons in an atom can have the same set of values of all four quantum numbers”.
Illustration: H(Z = 1) 1s1.
One electron is present in hydrogen atom, the four quantum numbers are n = 1, l = 0, m = 0 and s = `+1/2`. For helium Z = 2. He: 1s2. In this one electron has the quantum number same as that of hydrogen, n = 1, l = 0, m = 0 and s = `+1/2` For other electron, fourth quantum number is different, i.e. n = 1, l = 0, m = 0 and s = `-1/2`.
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