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Structure of Atom · Question 4

JEE Main 2026 (Online) 6th April Evening ShiftMCQEasy📈 Topic in 26% papers+4−1
1

The Bohr radius of a hydrogen like species is 70.53 pm. The species and the stationary state (n) are respectively (Given : Hydrogen atom Bohr radius is 52.9 pm)

  1. Li2+, 3
  2. He+, 3
  3. He+, 2
  4. Li2+, 2

Answer

(4) Li2+, 2

Solution

For a hydrogen-like species: rn = 52.9 n2Z pm

⇒ n2Z = 70.5352.9 = 1.333 = 43

⇒ n2 = 4 and Z = 3 ⇒ n = 2, Z = 3

∴ The species is Li2+ (Z = 3) in the stationary state n = 2.

(Check: He+, n = 3 gives 52.9 92 = 238 pm; Li2+, n = 3 gives 158.7 pm.)

Answer: (4)

JEE Main 2026 (Online) 6th April Evening Shift

Keep practising — Structure of Atom

2

Arrange the following atomic orbitals of multi electron atoms in order of increasing energy. Choose the correct answer from the options given below:

  1. C < D < B < A < E
  2. B < A < E < C < D
  3. E < C < D < B < A
  4. E < B < A < D < C
JEE Main 2026 (Online) 5th April Morning Shift
3

Identify the correct statements from the following : Choose the correct answer from the options given below:

  1. A, B and C Only
  2. A, B and D Only
  3. B, C and D Only
  4. A, C and D Only
JEE Main 2026 (Online) 5th April Morning Shift
4

Which of the following statement(s) is/are true ? Choose the correct answer from the options given below :

  1. A, B and C only
  2. A and C only
  3. C and D only
  4. A only
JEE Main 2026 (Online) 5th April Evening Shift
5

What is the ratio of wave number of first line (lowest energy line) of Balmer series of H atomic spectrum to first line of its Brackett series?

  1. 5 : 1
  2. 5 : 0.81
  3. 5 : 1.75
  4. 5 : 27
JEE Main 2026 (Online) 4th April Morning Shift
6

Which of the following is correct set of 4 quantum numbers of 19th electron in Chromium (Atomic number = 24) in accordance with Aufbau principle?

  1. n = 3, l = 2, m = +2, s = + 12
  2. n = 3, l = 2, m = -2, s = + 12
  3. n = 4, l = 1, m = 0, s = + 12
  4. n = 4, l = 0, m = 0, s = + 12
JEE Main 2026 (Online) 4th April Morning Shift
7

The species having identical radii according to the Bohr's theory are : Choose the correct answer from the options given below :

  1. A and C Only
  2. A and E Only
  3. B and E Only
  4. C and D Only
JEE Main 2026 (Online) 4th April Evening Shift
8

What is the energy (in J atom-1) required for the following process ? Li2+(g) Li3+(g) + e- (Take the ionization energy for the H atom in the ground state as 2.18 10-18 J atom-1)

  1. 8.72 10-18
  2. 1.962 10-18
  3. 1.962 10-17
  4. 6.54 10-17
JEE Main 2026 (Online) 2nd April Morning Shift
9

The surface of sodium metal is irradiated with radiation of wavelength x nm. The kinetic energy of ejected electrons is 2.8 10-20 J. The work function of sodium is 2.3 eV. The value of x is 102 nm. (Nearest integer) (Given : h = 6.6 10-34 J s; 1 eV = 1.6 10-19 J; c = 3.0 108 m s-1)

JEE Main 2026 (Online) 2nd April Evening Shift
10

The wave numbers of three spectral lines of H atom are considered. Identify the set of spectral lines belonging to Balmer series. (R = Rydberg constant)

  1. 5R36, 3R16, 21R100
  2. 7R144, 3R16, 16R255
  3. 3R4, 3R16, 7R144
  4. 5R36, 8R9, 15R16
JEE Main 2026 (Online) 28th January Morning Shift
11

[figure] Figure 1. electron probability density for 2s orbital [figure] Figure 2. wave function for 2s orbital Which of the following point in Figure 2 most accurately represents the nodal surface as shown in Figure 1?

  1. D
  2. B
  3. C
  4. A
JEE Main 2026 (Online) 28th January Morning Shift

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