Modern Physics 7 Question 37

39. If elements with principal quantum number $n>4$ were not allowed in nature, the number of possible elements would be

$(1983,1 M)$

(a) 60

(b) 32

(c) 4

(d) 64

Show Answer

Solution:

  1. The maximum number of electrons in an orbit are $2 n^{2}$. If $n>4$, is not allowed, then the number of maximum electrons that can be in first four orbit are :

$$ 2(1)^{2}+2(2)^{2}+2(3)^{2}+2(4)^{2}=2+8+18+32=60 $$

Therefore, possible elements can be 60 .



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