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GATE 2023 CY – Question 35

Inorganic Chemistry · Lanthanides and Actinides: Recovery. Periodic properties, spectral and magnetic properties. · 1 mark · Numerical answer

The calculated magnetic moment of $[Ce(NO_3)_5]^{2-}$ is ______ BM (two decimal places). Atomic number of Ce is 58.

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Correct answer: 2.51 to 2.55

Explanation

Five nitrate anions require Ce3+, which is 4f1. Hund rules give L=3, S=1/2, J=5/2 and Landé factor gJ=6/7.

Therefore μ=gJ√[J(J+1)]=(6/7)√(35/4)=2.53546 BM, rounded **2.54 BM**. Spin-only treatment is not appropriate for lanthanides.