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Question: Answered & Verified by Expert
In an atom the order of increasing energy of electrons with quantum numbers
(i) $n=4, l=1$
(ii) $n=4, l=0$
(iii) $n=3, l=2$ and (iv) $n=3, l=1$ is
ChemistryStructure of AtomTS EAMCETTS EAMCET 2014
Options:
  • A $\mathrm{iii} < $ (i) $ < \mathrm{iv} < $ ii
  • B $\mathrm{ii} < \mathrm{iv} < \mathrm{i} < \mathrm{iii}$
  • C $\mathrm{i} < \mathrm{iii} < \mathrm{ii} < \mathrm{iv}$
  • D iv $ < \mathrm{ii} < \mathrm{iii} < \mathrm{i}$
Solution:
1220 Upvotes Verified Answer
The correct answer is: iv $ < \mathrm{ii} < \mathrm{iii} < \mathrm{i}$
The order of increase of energy can be calculated from $(n+I)$ rule. If two orbitals have same value of $(n+I)$, the orbital with lower value of $n$ will be filled first.
(i) For $n=4, I=1,(n+I)=4+1=5$
(ii) For $n=4, l=0,(n+l)=4+0=4$
(iii) For $n=3, l=2,(n+l)=3+2=5$
(iv) For $n=3, I=1,(n+I)=3+1=4$
Therefore correct order is
(iv) $ < $ (ii) $ < $ (iii) $ < $ (i).

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