Answer : The number of electrons in an atom are, 2.
Explanation :
Principle Quantum Numbers : It describes the size of the orbital and the energy level. It is represented by n. Where, n = 1,2,3,4....
Azimuthal Quantum Number : It describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For l = 0,1,2,3... the orbitals are s, p, d, f...
Magnetic Quantum Number : It describes the orientation of the orbitals. It is represented as . The value of this quantum number ranges from . When l = 2, the value of will be -2, -1, 0, +1, +2.
Spin Quantum number : It describes the direction of electron spin. This is represented as The value of this is for upward spin and for downward spin.
As we are given that,
So,
(For each sub-shell)
From this we conclude that, that means there is one orbital that contains two electrons with opposite spin.
Hence, the number of electrons in an atom are, 2.