Information -1 : Principlal quantun number 'n' is defined as 1, 2, 3….
Information -2 : Azimaathal quantum number 'l' is defined as 0 to `(n + 1)` in integral steps of 1
Information -3 : Magnetic quantum number 'm' is defined as `- l //2` to `+ l//2`
Information -4 : Spin quantum number 's' has five possible values `-2, -10, +1, +2`
Information -5 : The sub-shell corresponding to `l = 1, 2, 3, 4, 5`..... designated as P, Q, R, S, T, U.... respectively.
Information -6 : The values of m for a given value of l give the number of orbitals in a sub-shell
Information -7 : The principles for filling electron in teh shells remains unchanged.
On the basic of above informations, answer the following questions.
For the element having atomic number 51, last electron enters in

Options

A. 2Q
B. 2R
C. 3Q
D. 3S

Answer

B

Explanation

`n = 1, 2, 3`………
`{:(n = 1,n = 2,n = 3,),(l = 0"," 1"," 2,l = 0","1","2","3,l = 0","1","2","3","4,):}`
Possible subshells -
`{:(,1P,1Q,1R,2P,2Q,2R,2S,3P,3Q........,),(n + l =,1,2,3,2,3,4,5,3,4........,):}`
Inceasing order of energy
Each orbital has 5 electrons.
`{:(,1P,1Q,2P,1R,2Q,3P,2R........),("Total electrons",5,10,5,15,10,5,):}`
`{:("Type of subshell",1P,1Q,2P,1R,2Q,),("Number of electrons accomodate by the given subshell",10,15,10,20,15,):}`
Sol.(i) `II^(nd)` period will be start from atomic number 16 (Sulphur)
Sol. (ii) Last electron from `Z = 50` to `Z = 65` will enter in 2R subshell
Sol. (iii) For T subshell `l = 4`. Number of possible values of `m = 5`, Total electron `= 25`