Number of  electrons  possible with n = 4, m = +1 and s=- 12 are

n = 4      l = 0    m = 0n = 4       l = 1    m = -1,0,+1n = 4      l = 2     m = –2,–1,0,+1,+2n = 4       l = 3    m = –3, –2, –1, 0, +1, +2, +3For each value of ‘m’(an orbital) two electrons with opposite spin are possiblePossible number of electrons with n = 4, m = +1n = 4,  l = 1  m = +1……..2 electronsn = 4,  l = 2  m = +1……2 electronsn = 4,  l = 3  m = +1……2 electrons      Total     6 electronsBut with s=- 12 only 3e-are possible