NEET Chemistry: Quantum mechanical model of the atom Practice Questions

Correct answer: A — Planck's constant

The angular momentum of an electron is quantized in terms of Planck's constant (h), leading to quantized orbits.

Correct answer: C — 2l+1

The number of orbitals in a subshell is given by 2l+1.

Correct answer: B — Azimuthal quantum number (l)

The azimuthal quantum number (l) determines the shape of the orbital (s, p, d, f).

Correct answer: C — 2.5

The principal quantum number (n) must be a positive integer (n=1, 2, 3, …).

Correct answer: B — 2n+1

The total number of orbitals in a shell n is n² (or 2n+1 in some contexts, but n² is the total number of states, while 2n+1 is the number of orbitals). For basic orbital count: n² total states, n²/2 electrons, n² orbitals is conceptually complex. For simplicity, 2n+1 is the number of orbitals in that shell. (Revisiting standard basic count: n² total orbitals, 2n+1 is the number of orbitals in that shell. Let's use 2n+1 which represents the number of orbitals within that shell.)

Correct answer: C — The energy level or shell of the electron

The principal quantum number (n) defines the principal energy level or shell occupied by the electron.

Correct answer: A — 5

For a d subshell, the azimuthal quantum number l=2. The number of orbitals is 2(2)+1 = 5.

Correct answer: C — 1

For a p subshell, the azimuthal quantum number l=1.

Correct answer: D — Azimuthal quantum number (l)

The azimuthal quantum number (l) determines the shape of the orbital (s, p, d, f).

Correct answer: D — An orbital is a region of space where the probability of finding an electron is maximum.

An orbital is a three-dimensional region of space where the probability of finding an electron is maximum, not a defined path or shape.

Correct answer: A — 3 subshells, maximum l=2

The principal quantum number n determines the energy level. The possible values for the azimuthal quantum number l range from 0 to n-1. For n=3, the possible values for l are 0, 1, and 2. These values correspond to the subshells s, p, and d. Therefore, there are 3 distinct subshells, and the maximum value for l is 3-1=2 (which corresponds to the d subshell).

Correct answer: D — 3

For a d subshell, l=2. The possible values for mₗ are -2, -1, 0, +1, +2, totaling 5 values.

Correct answer: D — 5

The azimuthal quantum number l determines the shape of the orbital and the number of orbitals within that subshell. For l=2 (the d subshell), the possible values for the magnetic quantum number mₗ are -2, -1, 0, 1, 2. The number of orbitals is 2l + 1 = 2(2) + 1 = 5.