J & K CET Engineering J and K - CET Engineering Solved Paper-2011

The electrons identified by quantum numbers n and I, (i) \[n=4,l=1,\](ii)\[~n=4,l=0\] (iii) \[n=3,l=2\]and (iv) \[n=3,l=1\]can be placed in order of increasing energy as

A) (i) < (ii) < (iii) < (iv)

B) (iv) < (iii) < (ii) < (i)

C) (iv) < (ii) < (iii) < (i)

D) (iv) < (i) < (ii) < (iii)

Correct Answer: C

Solution :

According to \[(n+l)\] rule, the lower the value of \[(n+l)\] for an orbital, the lower is its energy. If two orbitals have the same value of\[(n+l),\] the orbital with lower value of n will have the lower energy. Hence, the order of increasing energy of electron is as

\[\text{IV}\]	\[<\]	\[\text{II}\]	\[<\]	\[\text{III}\]	<	\[\text{I}\]
\[n=3\]		\[n=4\]		\[n=3\]		\[n=4\]
\[l=1\]		\[l=0\]		\[l=2\]		\[l=1\]
\[n+l=4\]		\[n+l=4\]		\[n+l=5\]		\[n+l=5\]

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