Which is the electron configuration for nobelium (No)?

Nobelium has atomic number 102, so its electron configuration must account for 102 electrons. The radon core, [Rn], accounts for 86; adding 7s² and 5f¹⁴ gives 86 + 2 + 14 = 102. Therefore, the configuration is [Rn]7s²5f¹⁴, choice A.

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