1
JEE Main 2026 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Identify the INCORRECT statements from the following :

A. Notation ${ }_{12}^{24} \mathrm{Mg}$ represents 24 protons and 12 neutrons.

B. Wavelength of a radiation of frequency $4.5 \times 10^{15} \mathrm{~s}^{-1}$ is $6.7 \times 10^{-8} \mathrm{~m}$.

C. One radiation has wavelength $=\lambda_1(900 \mathrm{~nm})$ and energy $=\mathrm{E}_1$. Other radiation has wavelength $=\lambda_2(300 \mathrm{~nm})$ and energy $=\mathrm{E}_2 \cdot \mathrm{E}_1: \mathrm{E}_2=3: 1$.

D. Number of photons of light of wavelength 2000 pm that provides 1 J of energy is $1.006 \times 10^{16}$.

Choose the correct answer from the options given below :

A

A and D Only

B

A and C Only

C

A and B Only

D

B and C Only

2
JEE Main 2026 (Online) 23rd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Given,

(A) $\mathrm{n}=5, \mathrm{~m}_1=-1$

(B) $\mathrm{n}=3, \mathrm{l}=2, \mathrm{~m}_1=-1, \mathrm{~m}_{\mathrm{s}}=+\frac{1}{2}$

The maximum number of electron(s) in an atom that can have the quantum numbers as given in (A) and (B) respectively are :

A

4 and 1

B

2 and 4

C

26 and 1

D

8 and 1

3
JEE Main 2026 (Online) 23rd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Which of the following statements regarding the energy of the stationary state is true in the following one - electron systems ?

A

$+2.18 \times 10^{-18} \mathrm{~J}$ for second orbit of $\mathrm{He}^{+}$ion

B

$+8.72 \times 10^{-18} \mathrm{~J}$ for first orbit of $\mathrm{He}^{+}$ion

C

$-1.09 \times 10^{-18} \mathrm{~J}$ for second orbit of H atom.

D

$-2.18 \times 10^{-18} \mathrm{~J}$ for third orbit of $\mathrm{Li}^{2+}$ ion

4
JEE Main 2026 (Online) 22nd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The energy of first (lowest) Balmer line of H atom is $x \mathrm{~J}$. The energy (in J) of second Balmer line of H atom is :

A

$\frac{x}{1.35}$

B

$1.35 x$

C

$x^2$

D

$2 x$

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