JEE Advanced levelNumerical answerDifficulty 3 of 3df208
Terbium has atomic number 65 and ground-state configuration [Xe]4f96s2. Calculate the spin-only magnetic moment of TbX4+ in BM, using μ=n(n+2) (answer to two decimals).
Numerical answer type, answer in BM, tolerance 0.01.
Answer: 7.94 BM
Removing 6s2 and two 4f electrons gives TbX4+ with 4f7, so n = 7 unpaired electrons. Spin-only μ=7×9=63=7.94 BM.