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

Given below are two statements :

Statement I : $\left[\mathrm{CoBr}_4\right]^{2-}$ ion will absorb light of lower energy than $\left[\mathrm{CoCl}_4\right]^{2-}$ ion.

Statement II : In $\left[\mathrm{CoI}_4\right]^{2-}$ ion, the energy separation between the two set of d-orbitals is more than $\left[\mathrm{CoCl}_4\right]^{2-}$ ion.

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

A

Both Statement I and Statement II are false

B

Both Statement I and Statement II are true

C

Statement I is false but Statement II is true

D

Statement I is true but Statement II is false

2
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

3
JEE Main 2026 (Online) 23rd January Morning Shift
Numerical
+4
-1
Change Language

The crystal field splitting energy of $\left[\mathrm{Co}(\text { oxalate })_3\right]^{3-}$ complex is ' $n^{\prime}$ times that of the $\left[\mathrm{Cr}(\text { oxalate })_3\right]^{3-}$ complex. Here ' $n$ ' is $\_\_\_\_$ . (Assume $\Delta_0 \gg P$ )

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4
JEE Main 2026 (Online) 23rd January Morning Shift
Numerical
+4
-1
Change Language

For the following gas phase equilibrium reaction at constant temperature,

$$ \mathrm{NH}_3(\mathrm{~g}) \rightleftharpoons 1 / 2 \mathrm{~N}_2(\mathrm{~g})+3 / 2 \mathrm{H}_2(\mathrm{~g}) $$

if the total pressure is $\sqrt{3} \mathrm{~atm}$ and the pressure equilibrium constant $\left(K_p\right)$ is 9 atm , then the degree of dissociation is given as $\left(x \times 10^{-2}\right)^{-1 / 2}$. The value of $x$ is $\_\_\_\_$ . (nearest integer)

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