Instead of principle quantum number (n), azimuthal quantum number (L) &magnetic quqntum number m,
a set of new quantum number s, t & u was introduce with similar logic but different value as defind
below
`s=1,2,3,...........oo` all positive integral values.
`t=(s^(2)-1^(1)),(s^(2)-2^(2)),(s^(2)-3^(3))`......... No negative value
`u=((t+1))/2"to"+((t+1))/2`(including zero , if any ) in integaral step .
Each orbital can have maximum four electrons .
(s+t) rule is defined ,similar to (n+l) rule.
Number of electronc for which s=2,t= 3 for an element with atomic number 24.

Options

A. 8
B. 4
C. 0
D. None of these

Answer

C

Explanation

`s=1" "t=0" "u=-(1)/(2),(1)/(2)`
`s=2" "t=0" "u =-(1)/(2),(1)/(2)`
`t=3" "u=-2,-1,0,+1,+2,`
` s=3" "t=0" "u=-(1)/(2),(1)/(2)`
`t=5" "u=-3,-2,-1,0,+1,+2,+3`
`t=8" "u=-(9)/(2),-(7)/(2),-(5)/(2),-(3)/(2),-(1)/(2),-(1)/(2),-(3)/(2),-(5)/(2),-(7)/(2),-(9)/(2)`
According to (s+1) rule increasing order of energy .
`1s" "2s" "3s" "4s" "2f" "5s`
(i) Number of electron in s `n=2" "7xx4=28`
Number of electron in s n=3" "`19xx4=76`" "Hence(B) ltbgt (ii) For `Z=24" "1s^(8)" "2s^(8)" "3s^(8)`i.e . number electron (s) in s=5" "t=3" "`[2f^(@)]`=0
(iii) Number of subshell in 's' shell is 3" " Hence(B)