Structure of Atom
29 Board Chemistry previous year questions on Structure of Atom — options free on every question; 3 include the answer & explanation free, the rest unlock with PYQ Pass.
In a multielectron atom, which of the following orbitals described by three quantum numbers will have same energy in absence of electric and magnetic fields?
A. \(n=1,1=0,{m}_{1}=0\)
B. \(n=2,1=0,{m}_{1}=0\)
C. \(n=2,1=1,{m}_{1}=1\)
D. \(n=3,1=2,{m}_{1}=1\)
E. \(n=3,1=2,{m}_{1}=0\)
Choose the correct answer from the options given below:
[JEE Main 2025, 28 Jan (Shift 1)]
D and E Only
In a multi-electron atom, the orbitals (D) n = 3, l = 2, m = 1 and (E) n = 3, l = 2, m = 0 described by the three quantum numbers will have the same energy in the absence of magnetic and electric fields.
D and E are 3d orbital.
For hydrogen atom, the orbital/s with lowest energy is/are :
(A) 4 s
(B) \(3{p}_{x}\)
(C) \(3{d}_{{x}^{2}-{y}^{2}}\)
(D) \(3{d}_{{z}^{2}}\)
(E) \(4{p}_{z}\)
Choose the correct answer from the options given below :
(B), (C) and (D) only
For H-atoms, orbitals in the shell are degenerate, meaning energy depends only on the value of ' n '.
\(∴{E}_{3{p}_{x}}={E}_{3{d}_{{x}^{2}-{y}^{2}}}={E}_{3{d}_{{z}^{2}}}\)
The four quantum numbers for the electron in the outer most orbital of potassium (atomic no. 19) are
\(\mathrm{n}=4,\mathrm{l}=0,\mathrm{m}=0,\mathrm{s}=+1/2\)
Step-by-step Short Solution:
- Potassium (Z = 19)
Electron configuration:
\[1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 4 s^1\]
- The outermost electron is in the 4 s orbital, so:
- Principal quantum number \(n=4\)
- Azimuthal quantum number \(l=0\) (since it's an 's' orbital)
- Magnetic quantum number \(m=0\) (only one value for \(l=0\) )
- Spin quantum number \(s=+\frac{1}{2}\) (assumed to be \(+1 / 2\) for the first electron)
Final Answer:
A) \(n=4, l=0, m=0, s=+\frac{1}{2}\)
Consider the ground state of chromium atom (Z = 24). How many electrons are with Azimuthal quantum number l = 1 and l = 2 respectively ?
[JEE Main 2025, 4 Apr (Shift 2)]
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Bohr's model is applicable for a single electron atom of atomic number Z. Dependency of frequency of rotation of electron in \({\mathrm{n}}^{\mathrm{th}}\) principal quantum number is proportional to (Memory Based Question 28/Jan/25 Evening shift)
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A photon of wavelength 3000 \(\overset{^\circ }{\mathrm{A}}\) strikes a metal surface. The work function of the metal is 2.13 eV. What is the kinetic energy of the emitted photoelectron?
(h = 6.626 × \({10}^{-34}\) Js)
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If radius of the first Bohr orbit of H-atom is \({\mathrm{a}}_{\mathrm{o}}\), then find the radius of 2nd Bohr's orbit of H-atom (memory based jee mains shift-1 29/01/2025)
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The extra stability of half-filled subshell is due to
(A) Symmetrical distribution of electrons
(B) Smaller coulombic repulsion energy
(C) The presence of electrons with the same spin in non-degenerate orbitals
(D) Larger exchange energy
(E) Relatively smaller shielding of electrons by one another
Identify the correct statements
[JEE Main 2025, 7 Apr (Shift 2)]
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An electron of \({\mathrm{He}}^{+}\) is present in 3rd excited state. Find its De-broglie wavelength.
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Given below are two statements :
Statement (I): It is impossible to specify simultaneously with arbitrary precision, both the linear momentum and the position of a particle.
Statement (II): If the uncertainty in the measurement of position and uncertainty in measurement of momentum are equal for an electron, then the uncertainty in the measurement of velocity is \(⩾\sqrt{\frac{h}{\pi }}\times \frac{1}{2m}\).
In the light of the above statements, choose the correct answer from the options given below :
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Correct statements for an element with atomic number 9 are
(i). There can be 5 electrons for which \({\mathrm{m}}_{\mathrm{s}}=+\frac{1}{2}\) and 4 electrons for which \({\mathrm{m}}_{\mathrm{s}}=-\frac{1}{2}\)
(ii). There is only one electron in \({p}_{z}\)orbital
(iii). The last electron goes to orbital with \(\mathrm{n}=2\) and \(l=1\)
(iv). The sum of angular nodes of all the atomic orbitals is 1 .
Choose the correct answer from the options given below:
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Radius of the first excited state of Helium ion is given as : \({a}_{0}\to\) radius of first stationary state of hydrogen atom
[JEE Main 2025, 22 Jan (Shift 1)]
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Consider the following statements :
(A) The principal quantum number ‘n’ is a positive integer with values of ‘n’ = 1, 2, 3, …
(B) The azimuthal quantum number ‘l’ for a given ‘n’ (principal quantum number) can have values as ‘l’ = 0, 1, 2, … n
(C) Magnetic orbital quantum number ‘ml ’for a particular ‘l’ (azimuthal quantum number) has (2l + 1)values.
(D) ±1/ 2 are the two possible orientations of electron spin.
(E) For l = 5,there will be a total of 9 orbital
Which of the above statements are correct ?
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Radius of electron in ground state for hydrogen is \({a}_{o}\), then radius of electron in \({\mathrm{He}}^{+}\)ion in \({3}^{\mathrm{rd}}\) excited state is a. Then \(\frac{{\mathrm{a}}_{\mathrm{o}}}{\mathrm{a}}\) is:
(Memory Based JEE Mains 22/01/2025,Shift -1)
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Radius of electron in ground state for hydrogen is \({a}_{o}\), then radius of electron in \({\mathrm{He}}^{+}\)ion in \({3}^{\mathrm{rd}}\) excited state is a. Then \(\frac{{\mathrm{a}}_{\mathrm{o}}}{\mathrm{a}}\) is:
(Memory Based JEE Mains 22/01/2025,Shift -1)
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If \({a}_{0}\) is denoted as the Bohr radius of hydrogen atom, then what is the de-Broglie wavelength \((\lambda )\) of the electron present in the second orbit of hydrogen atom? [n : any integer]
[JEE Main 2025, 29 Jan (Shift 1)]
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The four quantum numbers for the electron in the outer most orbital of potassium (atomic no. 19) are
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The correct order of energy of the following subshell is
1s, 2s, 3p, 3d
(Memory Based Question 28/Jan/25 Evening shift)
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The energy of an electron in the ground state (n = 1) for \({\mathrm{He}}^{+}\) ion is \(-\mathrm{x}\) Joules then that for an electron in n = 2 state for \({\mathrm{Be}}^{3+}\)ion in Joule is
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According to Bohr's model, the highest kinetic energy is associated with the electron in the:
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Heat treatment of muscular pain involves radiation of a wavelength of about 900 nm. Which spectral line of the H atom is suitable for this?
(Rydberg constant \({\mathrm{R}}_{\mathrm{H}}={10}^{5}{\mathrm{cm}}^{-1},\mathrm{h}=6.6\times {10}^{-34}\mathrm{Js},\mathrm{c}=3\times {10}^{8}\mathrm{m}/\mathrm{s}\))
[JEE Main 2025, 23 Jan (Shift 1)]
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The correct set of four quantum numbers for the valence electron of rubidium atom \((\mathrm{Z}=37)\) is :
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The quantum numbers of four electrons are given below
I. \(n=4 ; l=2 ; m_l=-2 ; s=-\frac{1}{2}\)
II. \(n=3 ; l=2 ; m_l=1 ; s=+\frac{1}{2}\)
III. \(n=4 ; l=1 ; m_l=0 ; s=+\frac{1}{2}\)
IV. \(n=3 ; l=1 ; m_l=-1 ; s=+\frac{1}{2}\)
The correct decreasing order of energy of these electrons is
[Re-NEET 2024]
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Which of the following energy order is correct for H-atoms?
Memory Based Question 28/Jan/25 Evening shift
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If the de-Broglie wavelength of a particle of mass (m) is 100 times its velocity,
then its value in terms of its mass (m) and Planck constant (h) is:
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Which of the following is/are not correct with respect to energy of atomic orbitals of hydrogen atom?
(A) 1s < 2p < 3d < 4s
(B) \(1s<2s=2p<3s=3p\)
(C) 1s < 2s < 2p < 3s < 3p
(D) \(1s<2s<4s<3d\)
Choose the correct answer from the options given below :
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Given below are two statements :
Statement (I) : A spectral line will be observed for a 2px → 2py transition.
Statement (II) : \(2{\mathrm{p}}_{\mathrm{x}}\mathrm{and}2{\mathrm{p}}_{\mathrm{y}}\)are degenerate orbitals.
In the light of the above statements, choose the correct answer from the options given below :
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If radius of the first Bohr orbit of H-atom is \({\mathrm{a}}_{\mathrm{o}}\), then find the radius of 2nd Bohr's orbit of H-atom (memory based jee mains shift-1 29/01/2025)
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Which of the following has the same energy in the absence of electric and magnetic field for the hydrogen atom? (Memory-based Question 28/ Jan/25 morning shift )
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