Question

Outermost electronic configuration of a group $13$ element, $\mathrm{E},$ is $4{ \mathrm{s}}^2,4{\mathrm{p}}^1.$ The electronic configuration of an element of p-block period-five placed diagonally to element, $\mathrm{E}$ is:

JEE Main 2021 (20 Jul Shift 2)

Options

• A: $\left[\mathrm{Kr}\right]3{ \mathrm{d}}^{10}4{ \mathrm{s}}^{2}4{\mathrm{p}}^2$
• B: $\left[\mathrm{Ar}\right]3{ \mathrm{d}}^{10}4{ \mathrm{s}}^{2}4{\mathrm{p}}^2$
• C: $\left[\mathrm{Xe}\right]5{ \mathrm{d}}^{10}6{ \mathrm{s}}^{2}6{\mathrm{p}}^2$
• D: $\left[\mathrm{Kr}\right]4{ \mathrm{d}}^{10}5{ \mathrm{s}}^{2}5{\mathrm{p}}^2$

Question

According to Bohr's atomic theory:
(A) Kinetic energy of electron is $\propto \frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}.$
(B) The product of velocity (v) of electron and principal quantum number $\left(\mathrm{n}\right), \text{'}vn\text{'}\propto {\mathrm{Z}}^2.$
(C) Frequency of revolution of electron in an orbit is $\propto \frac{{\mathrm{Z}}^3}{{\mathrm{n}}^3}.$
(D) Coulombic force of attraction on the electron is $\propto \frac{{\mathrm{Z}}^3}{{\mathrm{n}}^4}.$

Choose the most appropriate answer from the options given below:

JEE Main 2021 (24 Feb Shift 2)

Options

• A: (A), (C) and (D) only
• B: (A) and  (D) only
• C: (C) only
• D: (A) only

Question

A $50$ watt bulb emits monochromatic red light of wavelength of $795 \mathrm{nm}$. The number of photons emitted per second by the bulb is $x\times {10}^{20}.$ The value of $x$ is _____ .

(Nearest integer)

$\text{ [Given : }\left.\mathrm{h}=6.63\times {10}^{-34}\mathrm{Js}\text{ and} c=3.0\times {10}^8{ \mathrm{ms}}^{-1}\right]$

JEE Main 2021 (01 Sep Shift 2)

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Question

When light of wavelength $248 \mathrm{nm}$ falls on a metal of threshold energy $3.0 \mathrm{eV}$, the de-Broglie wavelength of emitted electrons is ________ $\stackrel{\mathrm{o}}{\mathrm{A}}$. (Round off to the Nearest Integer).

[Use : $\sqrt{3}=1.73, \mathrm{h}=6.63\times {10}^{-34} \mathrm{Js}; {\mathrm{m}}_{\mathrm{e}}=9.1\times {10}^{-31} \mathrm{kg}; \mathrm{c}=3.0\times {10}^8{ \mathrm{ms}}^{-1}; 1 \mathrm{eV}=1.6\times {10}^{-19} \mathrm{J}]$

JEE Main 2021 (16 Mar Shift 1)

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Question

The number of orbitals with $\mathrm{n}=5, {\mathrm{m}}_1=+2$ is ________. (Round off to the Nearest Integer).

JEE Main 2021 (16 Mar Shift 2)

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Question

The wavelength of electrons accelerated from rest through a potential difference of $40\mathrm{kV}$ is $\mathrm{X}\times {10}^{-12} \mathrm{m}.$ The value of $\mathrm{x}$ is. (Nearest integer)

Given: Mass of electron $=9.1\times {10}^{-31} \mathrm{kg}$

Charge on an electron $=1.6\times {10}^{-19}\mathrm{C}$

Planck's constant $=6.63\times {10}^{-34}\mathrm{Js}$

JEE Main 2021 (20 Jul Shift 2)

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Question

A source of monochromatic radiation wavelength $400 \mathrm{nm}$ provides $1000 \mathrm{J}$ of energy in $10$ seconds. When this radiation falls on the surface of sodium, $\mathrm{x}\times {10}^{20}$ electrons are ejected per second. Assume that wavelength $400 \mathrm{nm}$ is sufficient for ejection of electron from the surface of sodium metal. The value of $\mathrm{x}$ is ______. (Nearest integer)

$\left(\mathrm{h}=6.626\times {10}^{-34} \mathrm{Js}\right)$

JEE Main 2021 (25 Jul Shift 1)

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Question

The number of photons emitted by a monochromatic (single frequency) infrared range finder of power $1 \mathrm{mW}$ and wavelength of $1000 \mathrm{nm}$, in $0.1$ second is $\mathrm{x}\times {10}^{13}$. The value of $\mathrm{x}$ is (Nearest integer) $\left(\mathrm{h}=6.63\times {10}^{-34}\mathrm{Js}, \mathrm{c}=3.00\times {10}^8{ \mathrm{ms}}^{-1}\right)$:

JEE Main 2021 (27 Aug Shift 2)

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Question

The minimum uncertainty in the speed of an electron in one dimensional region of length $2{\mathrm{a}}_{\mathrm{o}}$
(Where ${\mathrm{a}}_{\mathrm{o}}=$ Bohr radius $52.9\mathrm{pm}$) is____${\mathrm{kms}}^{-1}$ (Nearest integer)  (Given : Mass of electron $=9.1\times {10}^{-31} \mathrm{kg}$, Planck's constant $\mathrm{h}=6.63\times {10}^{-34}\mathrm{Js}$)

JEE Main 2022 (29 Jul Shift 1)

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Question

The longest wavelength of light that can be used for the ionisation of lithium ion $\mathrm{(Li^{2+})}$ is $\mathrm{x}\times {10}^{-8} \mathrm{m}$. The value of $\mathrm{x}$ is (Nearest Integer)

(Given : Energy of the electron in the first shell of the hydrogen atom is $-2.2\times {10}^{-18} \mathrm{J}$; $\mathrm{h}=6.63\times {10}^{-34}\mathrm{Js}$ and $\mathrm{c}=3\times {10}^8{ \mathrm{ms}}^{-1}$)

JEE Main 2022 (25 Jun Shift 1)

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Question

Given below are two statements

Statement I : According to Bohr’s model of hydrogen atom, the angular momentum of an electron in a given stationary state is quantised.

Statement II : The concept of electron in Bohr’s orbit, violates the Heisenberg uncertainty principle. In the light of the above statements, choose the most appropriate answer from the options given below

JEE Main 2023 (15 Apr Shift 1)

Options

• A: Statement $\mathrm{I}$ is incorrect but Statement $\mathrm{II}$ is correct
• B: Both Statement $\mathrm{I}$ and Statement $\mathrm{II}$ are correct
• C: Both Statement $\mathrm{I}$ and Statement $\mathrm{II}$ are incorrect
• D: Statement $\mathrm{I}$ is correct but Statement $\mathrm{II}$ is incorrect

Question

The radius of the 2^nd orbit of ${\mathrm{Li}}^{2+}$ is $\mathrm{x}$. The expected radius of the 3^rd orbit of ${\mathrm{Be}}^{3+}$ is

JEE Main 2023 (25 Jan Shift 1)

Options

• A: $\frac{9}{4}\mathrm{x}$
• B: $\frac{4}{9}\mathrm{x}$
• C: $\frac{27}{16}\mathrm{x}$
• D: $\frac{16}{27}\mathrm{x}$

Question

Choose the Incorrect Statement about Dalton's Atomic Theory

JEE Main 2024 (04 Apr Shift 2)

Options

• A: chemical reactions involve reorganization of atoms
• B: Matter consists of indivisible atoms.
• C: Compounds are formed when atoms of different elements combine in any ratio.
• D: Compounds are formed when atoms of different elements combine in any ratio. All the atoms of a given element have identical properties including identical mass.

Question

Frequency of the de-Broglie wave of electron in Bohr's first orbit of hydrogen atom is _______ \(\times 10^{13} \mathrm{~Hz}\) (nearest integer). \(\begin{aligned} & \text { [Given : } \mathrm{R}_{\mathrm{H}}(\text { Rydberg constant })=2.18 \times 10^{-18} \mathrm{~J}, h \text { (Plank's } \\ & \text { constant })=6.6 \times 10^{-34} \mathrm{~J} \text {.s.] } \end{aligned}\)

JEE Main 2024 (06 Apr Shift 1)

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Question

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

JEE Main 2024 (09 Apr Shift 2)

Options

• A: \([\mathrm{Rn}] 5 \mathrm{f}^{10} 6 \mathrm{~d}^{\circ} 7 \mathrm{~s}^2\)
• B: \([\mathrm{Rn}] 5 \mathrm{f}^{13} 6 \mathrm{~d}^{\circ} 7 \mathrm{~s}^2\)
• C: \([\mathrm{Rn}] 5 \mathrm{f}^{11} 6 \mathrm{~d}^{\circ} 7 \mathrm{~s}^2\)
• D: \([\mathrm{Rn}] 5 \mathrm{f}^{12} 6 \mathrm{~d}^{\circ} 7 \mathrm{~s}^2\)

Question

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

JEE Main 2024 (09 Apr Shift 2)

Options

• A: A-III, B-II, C-I, D-IV
• B: A-II, B-I, C-IV, D-III
• C: A-I, B-IV, C-III, D-II
• D: A-IV, B-III, C-II, D-I

Question

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

JEE Main 2024 (31 Jan Shift 2)

Options

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

Question

The correct set of four quantum numbers for the valence electron of rubidium atom $(Z = 37)$ is:

JEE Main 2024 (29 Jan Shift 1)

Options

• A: $5,0,0,+\frac{1}{2}$
• B: $5,0,1,+\frac{1}{2}$
• C: $5,1,0,+\frac{1}{2}$
• D: $5,1,1,+\frac{1}{2}$

Question

The number of radial node/s for $3\mathrm{p}$ orbital is:

JEE Main 2024 (01 Feb Shift 2)

Options

• A: $1$
• B: $4$
• C: $2$
• D: $3$

Question

For hydrogen atom, energy of an electron in first excited state is \(-3.4 \mathrm{eV}, \mathrm{K} . \mathrm{E}\). of the same electron of hydrogen atom is \(x \mathrm{eV}\). Value of \(x\) is ______ \(\times 10^{-1} \mathrm{eV}\). (Nearest integer)

JEE Main 2024 (06 Apr Shift 2)

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