Answer
According to this principle two electrons in an atom cannot have same set of all the four quantum numbers.
In the given configurations, (a) and (b) violate Pauli’s exclusion principle.
In(a) the configuration is $1s^{3} $, $1s$ orbital contains 3 electrons and out of this two electrons have same set of all the four quantum numbers.
In(b) the configuration is $1s^{2} 2s^{2} 2p_{x}^{2} 2p_{y}^{3} $, $2p_{y}$ orbital contains 3 electrons and out of this two electrons have same set of all the four quantum numbers.
Hence the above two electronic configurations violate Paulis exclusion principle.
Work Step by Step
According to this principle two electrons in an atom cannot have same set of all the four quantum numbers.
In the given configurations, (a) and (b) violate Pauli’s exclusion principle.
In(a) the configuration is $1s^{3} $, $1s$ orbital contains 3 electrons and out of this two electrons have same set of all the four quantum numbers.
In(b) the configuration is $1s^{2} 2s^{2} 2p_{x}^{2} 2p_{y}^{3} $, $2p_{y}$ orbital contains 3 electrons and out of this two electrons have same set of all the four quantum numbers.
Hence the above two electronic configurations violate Paulis exclusion principle.
