Among the following, the energy of 2s orbital is lowest in:
- (A)K✓ Correct
- (B)Na
- (C)H
- (D)Li
Answer: (A)
Solution
Orbital energy drops as the effective nuclear charge rises, because the electron is held more tightly. Among , , and , potassium has the largest nuclear charge, so its electrons feel the strongest pull and the orbital lies lowest, most negative, in potassium.
JEE Main · 2019 · 12 Apr 2019 · Shift 2 · Single correct option