Structure of Atom · Question 1

JEE Advanced 2026 Paper 1Multiple CorrectMedium📈 Topic in 17% papers+4−1

The 2s and the 2p orbital energies of hydrogen atom are E2s(H) and E2p(H), respectively. The 2s and the 2p orbital energies of lithium atom are E2s(Li) and E2p(Li), respectively. The correct option(s) about the orbital energies is(are)

E2s(Li) < E2p(Li)
E2s(H) = E2p(H)
E2p(H) < E2s(Li)
E2s(H) > E2s(Li)

Answer

(1) E2s(Li) < E2p(Li), (2) E2s(H) = E2p(H), (4) E2s(H) > E2s(Li)

Solution

In a one-electron atom (H), the energy depends only on n, so E2s(H) = E2p(H) = -3.4 eV. (B) is correct.

In a multi-electron atom (Li), 2s penetrates closer to the nucleus than 2p, so E2s < E2p. (A) is correct.

Li 2s energy ≈ −(IE of Li) = −5.39 eV, which is lower than −3.4 eV. So E2s(H) > E2s(Li). (D) is correct.

For (C): E2p(H) = -3.4 eV is not lower than E2s(Li) = -5.39 eV, so (C) is wrong.

Answer: (A), (B), (D)

JEE Advanced 2026 Paper 1

Keep practising — Structure of Atom

Xa+ and Yb+ are hydrogen-like species. The wavelength of light absorbed during the transition between the states with principal quantum numbers n=1 and n=2 of Xa+ is . The wavelength of light absorbed during the transition between the states with principal quantum numbers n=2 and n=4 of Yb+ is 9 . The lowest possible value of (a+b) is .

JEE Advanced 2026 Paper 2

Among the following, the correct statement(s) for electrons in an atom is(are)

Uncertainty principle rules out the existence of definite paths for electrons.
The energy of an electron in 2s orbital of an atom is lower than the energy of an electron that is infinitely far away from the nucleus.
According to Bohr’s model, the most negative energy value for an electron is given by n = 1, which corresponds to the most stable orbit.
According to Bohr’s model, the magnitude of velocity of electrons increases with increase in values of n.

JEE Advanced 2024 Paper 1

According to Bohr’s model, the highest kinetic energy is associated with the electron in the

first orbit of H atom
first orbit of He+
second orbit of He+
second orbit of Li2+

JEE Advanced 2024 Paper 2

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