Atomic Structure · JEE Main previous year questions

2024 31 questions

1. Q692024 · 9 Apr 2024 · Shift 1

   The electronic configuration of $\mathrm{Cu}(\mathrm{II})$ is $3{\text{ d}}^9$ whereas that of $\mathrm{Cu}(\mathrm{I})$ is $3{\text{ d}}^{10}$. Which of the following is correct?

   1. A.$\mathrm{Cu}(\mathrm{II})$ is more stable
   2. B.$\mathrm{Cu}(\mathrm{II})$ is less stable
   3. C.$\mathrm{Cu}(\mathrm{I})$ and $\mathrm{Cu}(\mathrm{II})$ are equally stable
   4. D.Stability of $\mathrm{Cu}(\mathrm{I})$ and $\mathrm{Cu}(\mathrm{II})$ depends on nature of copper salts
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   Answer: A

2. Q772024 · 9 Apr 2024 · Shift 1

   Compare the energies of following sets of quantum numbers for multielectron system. (A) $n=4,l=1$ (B) $n=4,l=2$ (C) $n=3,l=1$ (D) $n=3,l=2$ (E) $n=4,l=0$ Choose the correct answer from the options given below :

   1. A.(E) > (C) > (A) > (D) > (B)
   2. B.(B) > (A) > (C) > (E) > (D)
   3. C.(C) < (E) < (D) < (A) < (B)
   4. D.(E) < (C) < (D) < (A) < (B)
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   Answer: C

3. Q782024 · 9 Apr 2024 · Shift 1

   Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : ${\mathrm{S}}_{\mathrm{N}}2$ reaction of ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{C}{\mathrm{H}}_2\mathrm{Br}$ occurs more readily than the ${\mathrm{S}}_{\mathrm{N}}2$ reaction of $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{Br}$. Reason (R) : The partially bonded unhybridized p-orbital that develops in the trigonal bipyramidal transition state is stabilized by conjugation with the phenyl ring. In the light of the above statements, choose the most appropriate answer from the options given below :

   1. A.Both (A) and (R) are correct but (R) is not the correct explanation of (A)
   2. B.Both (A) and (R) are correct and (R) is the correct explanation of (A)
   3. C.(A) is not correct but (R) is correct
   4. D.(A) is correct but (R) is not correct
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   Answer: B

4. Q632024 · 9 Apr 2024 · Shift 2

   Match List I with List II $$\begin{array}{llll}& \text{LIST I (Element)}& & \text{LIST II (Electronic Configuration)}\\ \text{A.}& \mathrm{N}& \text{I.}& [\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^{2}4{\mathrm{p}}^5\\ \text{B.}& \mathrm{S}& \text{II.}& [\mathrm{Ne}]3{\mathrm{s}}^{2}3{\mathrm{p}}^4\\ \text{C.}& \mathrm{Br}& \text{III.}& [\mathrm{He}]2{\mathrm{s}}^{2}2{\mathrm{p}}^3\\ \text{D.}& \mathrm{Kr}& \text{IV.}& [\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^{2}4{\mathrm{p}}^6\end{array}$$ Choose the correct answer from the options given below:

   1. A.A-IV, B-III, C-II, D-I
   2. B.A-I, B-IV, C-III, D-II
   3. C.A-III, B-II, C-I, D-IV
   4. D.A-II, B-I, C-IV, D-III
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   Answer: C

5. Q642024 · 9 Apr 2024 · Shift 2

   The electronic configuration of Einsteinium is : (Given atomic number of Einsteinium $=99$)

   1. A.$[\mathrm{Rn}]5{\mathrm{f}}^{13}6{\mathrm{d}}^{0}7{\mathrm{s}}^2$
   2. B.$[\mathrm{Rn}]5{\mathrm{f}}^{12}6{\mathrm{d}}^{0}7{\mathrm{s}}^2$
   3. C.$[\mathrm{Rn}]5{\mathrm{f}}^{11}6{\mathrm{d}}^{0}7{\mathrm{s}}^2$
   4. D.$[\mathrm{Rn}]5{\mathrm{f}}^{10}6{\mathrm{d}}^{0}7{\mathrm{s}}^2$
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   Answer: C

6. Q812024 · 9 Apr 2024 · Shift 2· Numerical answer

   Based on Heisenberg's uncertainty principle, the uncertainty in the velocity of the electron to be found within an atomic nucleus of diameter $10^{-15}\mathrm{m}$ is ____ $\times 10^9\mathrm{m}{\mathrm{s}}^{-1}$ (nearest integer) [Given : mass of electron $=9.1\times 10^{-31}\mathrm{kg}$, Planck's constant $(h)=6.626\times 10^{-34}\mathrm{Js}$] (Value of $\pi =3.14$)

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   Answer: 58

7. Q842024 · 9 Apr 2024 · Shift 2· Numerical answer

   Total number of electrons present in $({\pi }^{\ast })$ molecular orbitals of ${\mathrm{O}}_2$, ${\mathrm{O}}_2^{+}$ and ${\mathrm{O}}_2^{-}$ is ____.

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   Answer: 6

8. Q712024 · 8 Apr 2024 · Shift 1

   Number of Complexes with even number of electrons in ${\mathrm{t}}_{2g}$ orbitals is - $[\mathrm{Fe}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},[\mathrm{Co}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},[\mathrm{Co}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{3+},[\mathrm{Cu}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+},[\mathrm{Cr}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$

   1. A.3
   2. B.2
   3. C.1
   4. D.5
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   Answer: A

9. Q672024 · 8 Apr 2024 · Shift 2

   When ${\psi }_{\mathrm{A}}$ and ${\psi }_{\mathrm{B}}$ are the wave functions of atomic orbitals, then ${\sigma }^{\ast }$ is represented by :

   1. A.${\psi }_{\mathrm{A}}+2{\psi }_{\mathrm{B}}$
   2. B.${\psi }_{\mathrm{A}}-{\psi }_{\mathrm{B}}$
   3. C.${\psi }_{\mathrm{A}}-2{\psi }_{\mathrm{B}}$
   4. D.${\psi }_{\mathrm{A}}+{\psi }_{\mathrm{B}}$
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   Answer: B

10. Q732024 · 6 Apr 2024 · Shift 2

    Evaluate the following statements related to group 14 elements for their correctness. (A) Covalent radius decreases down the group from $\text{C}$ to $\text{Pb}$ in a regular manner. (B) Electronegativity decreases from $\text{C}$ to $\text{Pb}$ down the group gradually. (C) Maximum covalency of $\text{C}$ is 4 whereas other elements can expand their covalency due to presence of d orbitals. (D) Heavier elements do not form $\text{p}\pi -\text{p}\pi$ bonds. (E) Carbon can exhibit negative oxidation states. Choose the correct answer from the options given below :

    1. A.(A), (B) and (C) Only
    2. B.(A) and (B) Only
    3. C.(C), (D) and (E) Only
    4. D.(C) and (D) Only
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    Answer: C

11. Q902024 · 6 Apr 2024 · Shift 2· Numerical answer

    Total number of species from the following with central atom utilising ${\text{sp}}^2$ hybrid orbitals for bonding is ________. ${\text{NH}}_3,{\text{SO}}_2,{\text{SiO}}_2,{\text{BeCl}}_2,{\text{C}}_2{\text{H}}_2,{\text{C}}_2{\text{H}}_4,{\text{BCl}}_3,\text{HCHO},{\text{C}}_6{\text{H}}_6,{\text{BF}}_3,{\text{C}}_2{\text{H}}_4{\text{Cl}}_2$

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    Answer: 6

12. Q612024 · 5 Apr 2024 · Shift 2

    The number of complexes from the following with no electrons in the $t_2$ orbital is ____. $\mathrm{TiC}{\mathrm{l}}_4,[\mathrm{Mn}{\mathrm{O}}_4{]}^{-},[\mathrm{Fe}{\mathrm{O}}_4{]}^{2-},[\mathrm{FeC}{\mathrm{l}}_4{]}^{-},[\mathrm{CoC}{\mathrm{l}}_4{]}^{2-}$

    1. A.4
    2. B.2
    3. C.3
    4. D.1
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    Answer: C

13. Q692024 · 5 Apr 2024 · Shift 2

    Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : $\mathrm{N}{\mathrm{H}}_3$ and $\mathrm{N}{\mathrm{F}}_3$ molecule have pyramidal shape with a lone pair of electrons on nitrogen atom. The resultant dipole moment of $\mathrm{N}{\mathrm{H}}_3$ is greater than that of $\mathrm{N}{\mathrm{F}}_3$. Reason (R) : In $\mathrm{N}{\mathrm{H}}_3$, the orbital dipole due to lone pair is in the same direction as the resultant dipole moment of the $\mathrm{N}-\mathrm{H}$ bonds. $\mathrm{F}$ is the most electronegative element. In the light of the above statements, choose the correct answer from the options given below :

    1. A.(A) is false but (R) is true
    2. B.(A) is true but (R) is false
    3. C.Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
    4. D.Both (A) and (R) are true and (R) is the correct explanation of (A)
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    Answer: D

14. Q812024 · 5 Apr 2024 · Shift 2· Numerical answer

    In an atom, total number of electrons having quantum numbers $\mathrm{n}=4,|{\mathrm{m}}_l|=1$ and ${\mathrm{m}}_s=-\frac{1}{2}$ is ____.

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    Answer: 6

15. Q872024 · 4 Apr 2024 · Shift 1· Numerical answer

    The de-Broglie's wavelength of an electron in the $4^{\mathrm{th}}$ orbit is ____ $\pi {\mathrm{a}}_0$. (${\mathrm{a}}_0=$ Bohr's radius)

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    Answer: 8

16. Q632024 · 4 Apr 2024 · Shift 2

    If an iron (III) complex with the formula $[\text{Fe}({\text{NH}}_3{)}_x(\text{CN}{)}_y{]}^{-}$ has no electron in its $e_g$ orbital, then the value of $x+y$ is

    1. A.6
    2. B.4
    3. C.3
    4. D.5
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    Answer: A

17. Q812024 · 4 Apr 2024 · Shift 2· Numerical answer

    The maximum number of orbitals which can be identified with $n=4$ and $m_l=0$ is _________.

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    Answer: 4

18. Q732024 · 1 Feb 2024 · Shift 1
    
    1. A.
    2. B.
    3. C.
    4. D.
    Show answer

    Answer: D

19. Q732024 · 1 Feb 2024 · Shift 2

    Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In aqueous solutions ${\mathrm{Cr}}^{2+}$ is reducing while ${\mathrm{Mn}}^{3+}$ is oxidising in nature. Reason (R) : Extra stability to half filled electronic configuration is observed than incompletely filled electronic configuration. In the light of the above statements, choose the most appropriate answer from the options given below :

    1. A.(A) is true but (R) is false
    2. B.Both (A) and (R) are true and (R) is the correct explanation of (A)
    3. C.Both (A) and (R) are true but (R) is not the correct explanation of (A)
    4. D.(A) is false but (R) is true
    Show answer

    Answer: B

20. Q752024 · 1 Feb 2024 · Shift 2

    The number of radial node/s for $3p$ orbital is :

    1. A.3
    2. B.2
    3. C.1
    4. D.4
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    Answer: C

21. Q732024 · 31 Jan 2024 · Shift 1

    The linear combination of atomic orbitals to form molecular orbitals takes place only when the combining atomic orbitals A. have the same energy B. have the minimum overlap C. have same symmetry about the molecular axis D. have different symmetry about the molecular axis Choose the most appropriate from the options given below:

    1. A.B, C, D only
    2. B.A, B, C only
    3. C.B and D only
    4. D.A and C only
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    Answer: D

22. Q902024 · 31 Jan 2024 · Shift 1· Numerical answer

    The number of species from the following in which the central atom uses $\mathrm{s}{\mathrm{p}}^3$ hybrid orbitals in its bonding is ____. $\mathrm{N}{\mathrm{H}}_3,\mathrm{S}{\mathrm{O}}_2,\mathrm{Si}{\mathrm{O}}_2,\mathrm{BeC}{\mathrm{l}}_2,\mathrm{C}{\mathrm{O}}_2,{\mathrm{H}}_2\mathrm{O},\mathrm{C}{\mathrm{H}}_4,\mathrm{B}{\mathrm{F}}_3$

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    Answer: 4

23. Q732024 · 31 Jan 2024 · Shift 2

    The four quantum numbers for the electron in the outermost orbital of potassium (atomic no. 19) are

    1. A.$\mathrm{n}=3,l=0,\mathrm{m}=1,\mathrm{s}=+\frac{1}{2}$
    2. B.$\mathrm{n}=4,l=0,\mathrm{m}=0,s=+\frac{1}{2}$
    3. C.$\mathrm{n}=2,l=0,\mathrm{m}=0,s=+\frac{1}{2}$
    4. D.$\mathrm{n}=4,l=2,\mathrm{m}=-1,s=+\frac{1}{2}$
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    Answer: B

24. Q722024 · 30 Jan 2024 · Shift 1

    Given below are two statements : Statement (I) : The orbitals having same energy are called as degenerate orbitals. Statement (II) : In hydrogen atom, 3p and 3d orbitals are not degenerate orbitals. In the light of the above statements, choose the most appropriate answer from the options given below :

    1. A.Statement I is true but Statement II is false
    2. B.Statement I is false but Statement II is true
    3. C.Both Statement I and Statement II are false
    4. D.Both Statement I and Statement II are true
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    Answer: A

25. Q812024 · 30 Jan 2024 · Shift 1· Numerical answer

    The total number of molecular orbitals formed from $2s$ and $2p$ atomic orbitals of a diatomic molecule is _________.

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    Answer: 8