1
JEE Main 2026 (Online) 4th April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

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

A

$$ n=3, l=2, m=+2, s=+\frac{1}{2} $$

B

$$ n=3, l=2, m=-2, s=+\frac{1}{2} $$

C

$$ n=4, l=1, m=0, s=+\frac{1}{2} $$

D

$$ n=4, l=0, m=0, s=+\frac{1}{2} $$

2
JEE Main 2026 (Online) 2nd April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

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 $2.18 \times 10^{−18} \text{ J atom}^{−1}$)

A

$8.72 \times 10^{−18}$

B

$1.962 \times 10^{−18}$

C

$1.962 \times 10^{−17}$

D

$6.54 \times 10^{−17}$

3
JEE Main 2026 (Online) 28th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The wavelength of photon 'A' is 400 nm. The frequency of photon 'B' is $10^{16} \ \text{s}^{-1}$. The wave number of photon 'C' is $10^4 \ \text{cm}^{-1}$. The correct order of energy of these photons is :

A

A > C > B

B

C > B > A

C

B > A > C

D

A > B > C

4
JEE Main 2026 (Online) 28th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The wave numbers of three spectral lines of H atom are considered. Identify the set of spectral lines belonging to Balmer series.

( $\mathrm{R}=$ Rydberg constant)

A

$\frac{5 \mathrm{R}}{36}, \frac{3 \mathrm{R}}{16}, \frac{21 \mathrm{R}}{100}$

B

$\frac{7 \mathrm{R}}{144}, \frac{3 \mathrm{R}}{16}, \frac{16 \mathrm{R}}{255}$

C

$\frac{3 \mathrm{R}}{4}, \frac{3 \mathrm{R}}{16}, \frac{7 \mathrm{R}}{144}$

D

$\frac{5 \mathrm{R}}{36}, \frac{8 \mathrm{R}}{9}, \frac{15 \mathrm{R}}{16}$

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