Question

what principle is used in centrifugation give eg where this method is applied

Answer 1

Example you have taken Boron as an element. You have to memorize the names and their atomic number, that is going to help you here.
So,
The Element is Boron (B)
And its Atomic Number is 5
We will use this in shells(just like we have learned in finding the valency, remembered the orbit which we have made, like wise here also we have shells)
Tgere are 7 shells
K,L,M,N,O,P,Q.
K=2
L=8
M=18
N=32
O=18
P=8
Q= Sorry I forget the value :p
-------------------FILL IT------------------------------
ELEMENT = BORON
ATOMIC NUMBER =5
K=2, L=3
IT IS (2,3)
ELEMENT SODIUM
ATOMIC NUMBER = 11
K = 2, L= 8,M=1
You will write it like (2,8,1)

I don't know that I have understand your question or not but I have tried my best to answer you.
Well I have a lot of problems with this concept when I was new to it.
And I searched a lot but got nothing.
Glad to help you.
Please rate it.