1
JEE Main 2026 (Online) 24th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The correct order of $\mathrm{C}, \mathrm{N}, \mathrm{O}$ and F in terms of second ionisation potential is

A

$\mathrm{C}<\mathrm{N}<\mathrm{F}<\mathrm{O}$

B

$\mathrm{C}<\mathrm{F}<\mathrm{N}<\mathrm{O}$

C

$\mathrm{F}<\mathrm{N}<\mathrm{C}<\mathrm{O}$

D

$\mathrm{C}<\mathrm{O}<\mathrm{N}<\mathrm{F}$

2
JEE Main 2026 (Online) 24th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Given below are two statements :

Statement I : Cross aldol condensation between two different aldehydes will always produce four different products.

Statement II : When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH , it forms a condensation product with acetophenone only.

In the light of the above statements, choose the correct answer from the options given below

A

Statement I is true but Statement II is false

B

Both Statement I and Statement II are false

C

Both Statement I and Statement II are true

D

Statement I is false but Statement II is true

3
JEE Main 2026 (Online) 24th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Choose the INCORRECT statement

A

Carbon exhibits negative oxidation states along with +4 and +2 .

B

Carbon cannot exceed its covalency more than four.

C

Among the isotopes of carbon, ${ }^{13} \mathrm{C}$ is a radioactive isotope.

D

$\mathrm{CO}_2$ is the most acidic oxide among the dioxides of group of 14 elements.

4
JEE Main 2026 (Online) 24th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The wavelength of spectral line obtained in the spectrum of $\mathrm{Li}^{2+}$ ion, when the transition takes place between two levels whose sum is 4 and difference is 2 , is

A

$1.14 \times 10^{-6} \mathrm{~cm}$

B

$2.28 \times 10^{-6} \mathrm{~cm}$

C

$1.14 \times 10^{-7} \mathrm{~cm}$

D

$2.28 \times 10^{-7} \mathrm{~cm}$

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