iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 29th June Evening Shift
Which of the following is the correct plot for the probability density ${\psi ^2}$ (r) as a function of distance 'r' of the electron from the nucleus for 2s orbital?
A.
B.
C.
D.
Correct Answer: B
Explanation:
Formula for number of radial nodes in nth orbital = n - $l$ - 1
For 2s, number of radial nodes = 2 – 0 – 1 = 1 and value of ${\psi ^2}$ is always positive.
2022
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 29th June Morning Shift
Which of the following statements are correct?
(A) The electronic configuration of Cr is [Ar] 3d5 4s1.
(B) The magnetic quantum number may have a negative value.
(C) In the ground state of an atom, the orbitals are filled in order of their increasing energies.
(D) The total number of nodes are given by n $-$ 2.
Choose the most appropriate answer from the options given below :
A.
(A), (C) and (D) only
B.
(A) and (B) only
C.
(A) and (C) only
D.
(A), (B) and (C) only
Correct Answer: D
Explanation:
(A) Cr (24) = 1s2 2s2 2p6 3s2 3p6 3d5 4s1
= [Ar] 3d5 4s1
(B) Magnetic quantum number (m) values ranging from $-$ l to + l including zero.
$\therefore$ It can have negative value.
(C) According to Aufbau rule, electrons are filled first in these orbitals which have low energy.
$\therefore$ Statement C is correct.
(D) We know,
Number of Radial nodes = n $-$ l $-$ 1
and number of Angular nodes = l
$\therefore$ Total nodes = n $-$ l $-$ 1 + 1 = n $-$ 1
2022
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 28th June Evening Shift
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) $\pm$ 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?
A.
(A), (B) and (C)
B.
(A), (C), (D) and (E)
C.
(A), (C) and (D)
D.
(A), (B), (C) and (D)
Correct Answer: C
Explanation:
(A) Principle quantum number n is a positive integer and it's possible values are n = 1, 2, 3 ........
$\therefore$ A is correct.
(B) Azimuthal quantum number 'l' for a given 'n' can have values as l = 0, 1, 2 ....... (n $-$ 1)
$\therefore$ Statement B is wrong.
(C) Magnetic orbital quantum number ml for particular l has values from $-$ l to + 1 including zero means 2l + 1 values.
$\therefore$ Statement C is correct.
(D) $ \pm \,\,{1 \over 2}$ are the two possible orientation of electron spin.
$\therefore$ Statement D is correct.
(E) For l = 5, there will be a total of 11 orbitals.
$l$ = 0 $\Rightarrow$ 5 subshell
$l$ = 1 $\Rightarrow$ p subshell
$l$ = 2 $\Rightarrow$ d subshell
$l$ = 3 $\Rightarrow$ f subshell
$l$ = 4 $\Rightarrow$ g subshell
$l$ = 5 $\Rightarrow$ h subshell
We know,
Number of orbital in any subshell = 2$l$ + 1.
$\therefore$ For h subshell, number of orbitals = 2 $\times$ 5 + 1 = 11
2022
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 26th June Evening Shift
The number of radial and angular nodes in 4d orbital are, respectively
A.
1 and 2
B.
3 and 2
C.
1 and 0
D.
2 and 1
Correct Answer: A
Explanation:
We know,
Radial nodes = n $-$ l $-$ 1
and Angular nodes = l
For 4d orbital,
n = 4
l = 2
$\therefore$ Radial nodes = 4 $-$ 2 $-$ 1 = 1
Angular nodes = 2
2022
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 26th June Morning Shift
If the radius of the 3rd Bohr's orbit of hydrogen atom is r3 and the radius of 4th Bohr's orbit is r4. Then :
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 24th June Morning Shift
Consider the following pairs of electrons
(A) (a) n = 3, $l$ = 1, m1 = 1, ms = + ${1 \over 2}$
(b) n = 3, 1 = 2, m1 = 1, ms = + ${1 \over 2}$
(B) (a) n = 3, $l$ = 2, m1 = $-$2, ms = $-$${1 \over 2}$
(b) n = 3, $l$ = 2, m1 = $-$1, ms = $-$${1 \over 2}$
(C) (a) n = 4, $l$ = 2, m1 = 2, ms = + ${1 \over 2}$
(b) n = 3, $l$ = 2, m1 = 2, ms = + ${1 \over 2}$
The pairs of electrons present in degenerate orbitals is/are :
A.
Only (A)
B.
Only (B)
C.
Only (C)
D.
(B) and (C)
Correct Answer: B
Explanation:
For degenerate orbitals, only the value of m must
be different. The value of (n + l) must be the
same.
Hence, the pair of electrons with quantum numbers
given in (B) are degenerate.
2022
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 29th July Morning Shift
The minimum uncertainty in the speed of an electron in an one dimensional region of length $2 \mathrm{a}_{\mathrm{o}}$ (Where $\mathrm{a}_{\mathrm{o}}=$ Bohr radius $52.9 \,\mathrm{pm}$) is _________ $\mathrm{km} \,\mathrm{s}^{-1}$.
(Given : Mass of electron = 9.1 $\times$ 10$-$31 kg, Planck's constant h = 6.63 $\times$ 10$-$34 Js)
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 28th July Evening Shift
If the wavelength for an electron emitted from $\mathrm{H}$-atom is $3.3 \times 10^{-10} \mathrm{~m}$, then energy absorbed by the electron in its ground state compared to minimum energy required for its escape from the atom, is _________ times. (Nearest integer)
$\left[\right.$ Given $: \mathrm{h}=6.626 \times 10^{-34} \mathrm{~J} \mathrm{~s}$ ]
Mass of electron $=9.1 \times 10^{-31} \mathrm{~kg}$
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 26th July Evening Shift
Consider an imaginary ion ${ }_{22}^{48} \mathrm{X}^{3-}$. The nucleus contains '$a$'% more neutrons than the number of electrons in the ion. The value of 'a' is _______________. [nearest integer]
Correct Answer: 4
Explanation:
Number of electrons in ${ }_{22}^{48} X^{3-}$ is 25 .
Number of neutrons $=48-22=26$.
$\%$ increase in the number of neutrons over electrons
$
=\left(\frac{26-25}{25}\right) 100=4 \%
$
$\therefore a=4$
2022
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 26th July Morning Shift
The wavelength of an electron and a neutron will become equal when the velocity of the electron is $x$ times the velocity of neutron. The value of $x$ is ____________. (Nearest Integer)
(Mass of electron is $9.1 \times 10^{-31} \mathrm{~kg}$ and mass of neutron is $1.6 \times 10^{-27} \mathrm{~kg}$ )
Hence maximum number of emission lines observed are $10 .$
2022
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 28th June Morning Shift
If the work function of a metal is 6.63 $\times$ 10$-$19J, the maximum wavelength of the photon required to remove a photoelectron from the metal is ____________ nm. (Nearest integer)
[Given : h = 6.63 $\times$ 10$-$34 J s, and c = 3 $\times$ 108 m s$-$1]
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 27th June Evening Shift
Consider the following set of quantum numbers.
n
1
m$_1$
A.
3
3
$ - $3
B.
3
2
$ - $2
C.
2
1
+1
D.
2
2
+2
The number of correct sets of quantum numbers is __________.
Correct Answer: 2
Explanation:
For A,
Given n = 3 and l = 3
but we know maximum value of l = n $-$ 1.
$\therefore$ l can't be equal to n.
So, Set A of quantum numbers is not possible.
For B,
Given n = 3, l = 2, m = $-$ 2
Here, l = 2 which follow the rule l = n $-$ 1.
And we know possible value of m is $-$ l to + l.
here possible value of m = $-$2 to +2
$\therefore$ This Set B is valid set of quantum numbers.
For C,
Given n = 2, l = 1, m = +1
Here l = 1 which follows the rule l = n $-$ 1.
For l = 1 possible value of m = $-$1 to +1
Here m = +1. So value of m is valid.
$\therefore$ Set C is valid set of quantum numbers.
For D,
Given n = 2, l = 2, m = +2
l = 2 does not follow the rule l = n $-$ 1 rule.
$\therefore$ Set D is not valid set of quantum numbers.
2022
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 27th June Morning Shift
If the uncertainty in velocity and position of a minute particle in space are, 2.4 $\times$ 10$-$26 (m s$-$1) and 10$-$7 (m) respectively. The mass of the particle in g is ____________. (Nearest integer)
(Given : h = 6.626 $\times$ 10$-$34 Js)
Correct Answer: 22
Explanation:
We know from hisenberg uncertainty principle
$\Delta x\,.\,\Delta p = {h \over {4\pi }}$
$ \Rightarrow \Delta x\,.\,m\Delta v = {h \over {4\pi }}$
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2022 (Online) 25th June Morning Shift
The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is x $\times$ 10$-$8 m. The value of x is ___________. (Nearest Integer).
(Given : Energy of the electron in the first shell of the hydrogen atom is $-$2.2 $\times$ 10$-$18 J ; h = 6.63 $\times$ 10$-$34 Js and c = 3 $\times$ 108 ms$-$1)
Correct Answer: 4
Explanation:
Bohr model is not valid for lithium atom (Li) as Bohr model is valid for only single electronic species, so it would be valid for Li+2 but not Li atom.
For diatomic molecules, the correct statement(s) about the molecular orbitals formed by the overlap of two $2 p_{z}$ orbitals is(are)
A.
$\sigma$ orbital has a total of two nodal planes.
B.
$\sigma^{*}$ orbital has one node in the $x z$-plane containing the molecular axis.
C.
$\pi$ orbital has one node in the plane which is perpendicular to the molecular axis and goes through the center of the molecule.
D.
$\pi^{*}$ orbital has one node in the $x y$-plane containing the molecular axis.
Correct Answer: A,D
Explanation:
Option (A) is correct.
Option (B) is incorrect.
$\pi^*$ orbital has zero node is the plane which is perpendicular to the molecular axis and goes through the center of molecule.
So, option (C) is incorrect.
$\pi^*$ Orbital has one node in the $x y-$ plane containing the molecular axis.
Option (D) is correct.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 26th August Morning Shift
Given below are two statements.
Statement I : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in positive charges on the nucleus as there is no strong hold on the electron by the nucleus.
Statement II : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in principal quantum number.
In the light of the above statements, choose the most appropriate 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
Correct Answer: C
Explanation:
Velocity of electron in Bohr's atom is given by
$V \propto {Z \over n}$
Z = atomic number of atom, corresponds to +ve charge so as Z increase velocity increases so statement I is wrong and as 'n' decreases velocity increases so statement II is correct.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 27th July Evening Shift
If the Thompson model of the atom was correct, then the result of Rutherford's gold foil experiment would have been :
A.
All of the $\alpha$-particles pass through the gold foil without decrease in speed.
B.
$\alpha$-particles are deflected over a wide range of angles.
C.
All $\alpha$-particles get bounced back by 180$^\circ$
D.
$\alpha$-particles pass through the gold foil deflected by small angles and with reduced speed.
Correct Answer: D
Explanation:
As in Thompson model, protons are diffused (charge is not centred) $\alpha$-particles deviate by small angles and due to repulsion from protons, their speed decreases.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 27th July Morning Shift
Given below are two statements :
Statement I : Rutherford's gold foil experiment cannot explain the line spectrum of hydrogen atom.
Statement II : Bohr's model of hydrogen atom contradicts Heisenberg' uncertainty principle.
In the light of the above statements, choose the most appropriate answer from the options given below :
A.
Statement I is false but statement II is true.
B.
Statement I is true but statement II is false.
C.
Both statement I and statement II are false.
D.
Both statement I and statement II are true.
Correct Answer: D
Explanation:
Rutherford's gold foil experiment only proved that electrons are held towards nucleus by electrostatic forces of attraction and move in circular orbits with very high speeds.
Bohr's model gave exact formula for simultaneous calculation of speed & distance of electron from the nucleus, something which was deemed impossible according to Heisenberg.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 20th July Evening Shift
Outermost electronic configuration of a group 13 element, E, is 4s2, 4p1. The electronic configuration of an element of p-block period-five placed diagonally to element, E is :
A.
[Kr] 3d10 4s2 4p2
B.
[Ar] 3d10 4s2 4p2
C.
[Xe] 5d10 6s2 6p2
D.
[Kr] 4d10 5s2 5p2
Correct Answer: D
Explanation:
The element E is Ga and the diagonal element of 5th period is ${}_{50}Sn$ having outer electronic configuration will be [Kr] 4d10 5s2 5p2.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 18th March Evening Shift
Given below are two statements :
Statement I : Bohr's theory accounts for the stability and line spectrum of Li+ ion.
Statement II : Bohr's theory was unable to explain the splitting of spectral lines in the presence of a magnetic field.
In the light of the above statements, choose the most appropriate answer from the options given below :
A.
Statement I is false but statement II is true.
B.
Both statement I and statement II are true.
C.
Statement I is true but statement II is false.
D.
Both statement I and statement II are false.
Correct Answer: A
Explanation:
Bohr’s theory is applicable for unielectronic species only
Li+ has two electrons.
Bohr’s theory could not explain the splitting of
spectral lines in the presence of external magnetic
field (Zeeman effect)
Statement I – false
Statement II – true
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 18th March Morning Shift
A certain orbital has no angular nodes and two radial nodes. The orbital is :
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 26th February Evening Shift
Which of the following forms of hydrogen emits low energy $\beta$- particles?
A.
Tritium $_1^3$H
B.
Proton H+
C.
Protium $_1^1$H
D.
Deuterium $_1^2$H
Correct Answer: A
Explanation:
Tritium isotope of hydrogen is radioactive and emits low energy $\beta ^-$ particles. It is because of high n/p ratio of tritium which makes nucleus unstable.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 26th February Morning Shift
The orbital having two radial as well as two angular nodes is :
A.
3p
B.
5d
C.
4d
D.
4f
Correct Answer: B
Explanation:
Number of radial nodes = (n – l – 1)
Number of angular nodes = l
for 5d; n = 5, l = 2
5d orbital has two radial nodes and two angular nodes
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 25th February Morning Shift
The plots of radial distribution functions for various orbitals of hydrogen atom against 'r' are given below :
The correct plot for 3s orbital is :
A.
(B)
B.
(A)
C.
(C)
D.
(D)
Correct Answer: D
Explanation:
Number of radial nodes = n – (l + 1)
For 3s orbital n = 3, l = 0
Number of radial nodes = 3 – 0 – 1 = 2
It is correctly represented in graph of option D.
2021
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 24th February Evening Shift
According to Bohr's atomic theory :
(A) Kinetic energy of electron is $ \propto {{{Z^2}} \over {{n^2}}}$.
(B) The product of velocity (v) of electron and principal quantum number (n), $'vn' \propto {Z^2}$.
(C) Frequency of revolution of electron in an orbit is $ \propto {{{Z^3}} \over {{n^3}}}$.
(D) Coulombic force of attraction on the electron is $ \propto {{{Z^3}} \over {{n^4}}}$.
Choose the most appropriate answer from the options given below :
A.
(A), (C) and (D) only
B.
(A) only
C.
(C) only
D.
(A) and (D) only
Correct Answer: D
Explanation:
According to Bohr's theory,
I. $KE \propto {{{Z^2}} \over {{n^2}}}$ or $13.6 \propto {{{Z^2}} \over {{n^2}}}{{(eV)} \over {(atom)'}}$
($\therefore$ Correct)
II. Speed of electron $ \propto {Z \over n}$
(Here, Z = atomic number, n = number of shells)
$\therefore$ $v \times n \propto Z$ ($\therefore$ Incorrect)
III. Frequency of revolution of electron $ = {v \over {2\pi r}}$
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 1st September Evening Shift
A 50 watt bulb emits monochromatic red light of wavelength of 795 nm. The number of photons emitted per second by the bulb is x $\times$ 1020. The value of x is __________. [Given : h = 6.63 $\times$ 10$-$34 Js and c = 3.0 $\times$ 108 ms$-$1]
Correct Answer: 2
Explanation:
Energy of photon is given as $E = {{nhc} \over \lambda }$ .... (i)
where, E = energy of photon (50 W),
n = number of photon
h = Planck's constant (6.63 $\times$ 10$-$34 Js)
c = speed of light (3 $\times$ 108 m/s)
$\lambda$ = wavelength of light (795 $\times$ 10$-$9 m)
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 31st August Morning Shift
Ge(Z = 32) in its ground state electronic configuration has x completely filled orbitals with ml = 0. The value of x is ___________.
Correct Answer: 7
Explanation:
Completely filled orbital with ml = 0 are
= 1 + 1 + 1 + 1 + 1 + 1 + 1
= 7
So, answer is 7.
2021
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 27th August Evening Shift
The number of photons emitted by a monochromatic (single frequency) infrared range finder of power 1 mW and wavelength of 1000 nm, in 0.1 second is x $\times$ 1013. The value of x is _____________. (Nearest integer)
$\Rightarrow$ n = 5.02 $\times$ 1014 = 50.2 $\times$ 1013
$\Rightarrow$ 50 (nearest integer)
2021
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 27th August Morning Shift
The kinetic energy of an electron in the second Bohr orbit of a hydrogen atom is equal to ${{{h^2}} \over {xma_0^2}}$. The value of 10x is ___________. (a0 is radius of Bohr's orbit) (Nearest integer) [Given : $\pi$ = 3.14]
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 26th August Evening Shift
A metal surface is exposed to 500 nm radiation. The threshold frequency of the metal for photoelectric current is 4.3 $\times$ 1014 Hz. The velocity of ejected electron is ____________ $\times$ 105 ms$-$1 (Nearest integer)
[Use : h = 6.63 $\times$ 10$-$34 Js, me = 9.0 $\times$ 10$-$31 kg]
Correct Answer: 5
Explanation:
$\upsilon $ : speed of electron having max. K.E.
$\Rightarrow$ from Einstein equation : E = $\phi$ + K.E.max
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 25th July Evening Shift
An accelerated electron has a speed of 5 $\times$ 106 ms$-$1 with an uncertainty of 0.02%. The uncertainty in finding its location while in motion is x $\times$ 10$-$9 m. The value of x is ____________. (Nearest integer)
[Use mass of electron = 9.1 $\times$ 10$-$31 kg, h =6.63 $\times$ 10$-$34 Js, $\pi$ = 3.14]
Correct Answer: 58
Explanation:
$\Delta v = {{0.02} \over {100}} \times 5 \times {10^6} = {10^3}$ m/s
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 25th July Morning Shift
A source of monochromatic radiation of wavelength 400 nm provides 1000 J of energy in 10 seconds. When this radiation falls on the surface of sodium, x $\times$ 1020 electrons are ejected per second. Assume that wavelength 400 nm is sufficient for ejection of electron from the surface of sodium metal. The value of x is ______________. (Nearest integer)
(h = 6.626 $\times$ 10$-$34 Js)
Correct Answer: 2
Explanation:
Total energy provided by
Source per second = ${{1000} \over {10}} = 100$ J
Energy required to eject electron = ${{hc} \over \lambda }$
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 20th July Evening Shift
The wavelength of electrons accelerated from rest through a potential difference of 40 kV is x $\times$ 10$-$12 m. The value of x is ___________. (Nearest integer)
Give : Mass of electron = 9.1 $\times$ 10$-$31 kg
Charge on an electron = 1.6 $\times$ 10$-$19 C
Planck's constant = 6.63 $\times$ 10$-$34 Js
Correct Answer: 6
Explanation:
Wavelength of electron is given by
$\lambda = {h \over {\sqrt {2mqV} }}$
Here q = charge on electron, V = potential difference
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 20th July Morning Shift
The Azimuthal quantum number for the valence electrons of Ga+ ion is ___________.
(Atomic number of Ga = 31)
Correct Answer: 0
Explanation:
Ga = 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1
Ga+
= 1s2 2s2 2p6 3s2 3p6 3d10 4s2
Azimuthal Quantum number (l) for valence shell electron is 0.
2021
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 17th March Morning Shift
A certain orbital has n = 4 and mL = $-$3. The number of radial nodes in this orbital is ____________. (Round off to the Nearest Integer).
Correct Answer: 0
Explanation:
Number of radial nodes = n – $\ell $ – 1
n = 4, mL =–3 so $\ell $ = 3
radial nodes = 4 – 3 – 1 = 0
2021
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 16th March Evening Shift
The number of orbitals with n = 5, m1 = +2 is ___________. (Round off to the Nearest Integer).
Correct Answer: 3
Explanation:
Given, n = 5, ml = + 2
For n = 5, possible value of l = 0, 1, 2, 3, 4
For l = 0, ml = 0
l = 1, ml = $-$1, 0, 1
l = 2, ml = $-$2, $-$1, 0, 1, 2
l = 3, ml = $-$3, $-$2, $-$1, 0, 1, 2, 3
l = 4, ml = $-$4, $-$3, $-$2, $-$1, 0, 1, 2, 3, 4
Possible value of ml for a given value of l
= 0, $\pm$ 1, $\pm$ 2, $\pm$ 3 ..... $\pm$ l
So, number of orbitals having n = 5 and ml = $\pm$ 2 are 3.
2021
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 16th March Morning Shift
When light of wavelength 248 nm falls on a metal of threshold energy 3.0 eV, the de-Broglie wavelength of emitted electrons is _______$\mathop A\limits^o $. (Round off to the Nearest Integer).
[ Use : $\sqrt 3 $ = 1.73, h = 6.63 $\times$ 10$-$34 Js
me = 9.1 $\times$ 10$-$31 kg; c = 3.0 $\times$ 108 ms$-$1; 1eV = 1.6 $\times$ 10$-$19 J]
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 26th February Evening Shift
A ball weighing 10 g is moving with a velocity of 90 ms$-$1. If the uncertainty in its velocity is 5%, then the uncertainty in its position is ___________ $\times$ 10$-$33 m. (Rounded off to the nearest integer)
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 25th February Evening Shift
Electromagnetic radiation of wavelength 663 nm is just sufficient to ionise the atom of metal A. The ionization enegy of metal A in kJ mol$-$1 is __________. (Rounded off to the nearest integer)
[h = 6.63 $\times$ 10$-$34 Js, c = 3.00 $\times$ 108 ms$-$1, NA = 6.02 $\times$ 1023 mol$-$1]
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 25th February Evening Shift
Among the following, number of metal/s which can be used as electrodes in the photoelectric cell is _________. (Integer answer)
(A) Li
(B) Na
(C) Rb
(D) Cs
Correct Answer: 1
Explanation:
Among the given alkali metals, only cesium (Cs)
is used as electrode in the photoelectric cell
due to its lowest ionisation energy.
2021
JEE Mains
Numerical
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2021 (Online) 24th February Morning Shift
A proton and a Li3+ nucleus are accelerated by the same potential. If $\lambda _{Li}$ and $\lambda _p$ denote the
de Broglie wavelengths of Li3+ and proton respectively, then the value of
${{{\lambda _{Li}}} \over {{\lambda _p}}}$ is x $ \times $ 10-1.
The value of x is ______. (Rounded off to the nearest integer)
[Mass of Li3+ = 8.3 mass of proton]
Correct Answer: 2
Explanation:
Given, mass of Li3+ = 8.3 times of mass of proton formula,
Consider a helium (He) atom that absorbs a photon of wavelength 330 nm. The change in the velocity (in cm s$-$1) of He atom after the photon absorption is __________.
(Assume : Momentum is conserved when photon is absorbed.
Use : Planck constant = 6.6 $\times$ 10$-$34 J s, Avogadro number = 6 $\times$ 1023 mol$-$1, Molar mass of He = 4 g mol$-$1)
Correct Answer: 30
Explanation:
Wavelength of photon absorbed, $\lambda$ = 330 nm = 330 $\times$ 10$-$9 m
Planck's constant, h = 6.6 $\times$ 10$-$34 J s
Molar mass of He, M = 4 g mol$-$1 = 4 $\times$ 10$-$3 kg mol$-$1
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2020 (Online) 5th September Evening Slot
The correct statement about probability density (except at infinite distance from nucleus) is :
A.
It can be zero for 1s orbital
B.
It can be zero for 3p orbital
C.
It can never be zero for 2s orbital
D.
It can negative for 2p orbital
Correct Answer: B
Explanation:
$\phi $2 (probability density) can be zero for 3p
orbital other than infinite distance. It has one
radial node.
2020
JEE Mains
MCQ
iCON Education HYD, 79930 92826, 73309 72826JEE Main 2020 (Online) 5th September Morning Slot
The difference between the radii of 3rd and 4th orbits of Li2+ is R1
. The difference between the
radii of 3rd and 4th orbits of He+ is
$\Delta $R2
. Ratio $\Delta $R1 : $\Delta $R2 is :
