The term symbol for the ground state of a metal ion is ${ }^{3} \mathrm{P}_{2}$. The residual entropy of a crystal of a salt of this metal ion at 0 K is :
(a)$\mathrm{k}_{\mathrm{B}} \ln 1$
(b)$\mathrm{k}_{\mathrm{B}} \ln 3$
(c)$\mathrm{k}_{\mathrm{B}} \ln 5$
(d)$\mathrm{k}_{\mathrm{B}} \ln 7$
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed D; on checking, C is correct — see the explanation.
Printed D; the degeneracy is 2J + 1 with J = 2.
Explanation
A ³P₂ level is (2J + 1) = 5-fold degenerate, so the residual entropy is k_B ln 5 per ion.