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NEET Chemistry MCQ
Structure Of Atom Mcq Neet Chemistry
Quiz 2
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Q.1
The postulate that all atoms of an element are exactly alike was proved wrong with the discovery of
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a)radioactivity
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b) allotropy
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c)isotopes
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d)isobars
Explanation
Answer: (c)
Q.2
The introduction of neutron into the nucleus of an atom would lead to change in
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a) The number of electrons also
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b) The chemical nature of atom
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c)Its atomic number
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d)Its atomic weight
Explanation
Answer: (d)
Q.3
Which of the following is discrete in Bohr's theory
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a) Potential energy
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b) Kinetic energy
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c)Velocity
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d)Angular momentum
Explanation
Angular momentum=n (h/2π) HEre n=1, 2, 3 ,..... Answer:(d)
Q.4
Which of the following statement is not correct
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a) Angular momentum of 3s electron is equal to that of 2s electron
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b) Energy levels of H-atom are not equally spaced
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c) Energy of electron is zero only when it is stationary
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d) Humphrey series lies in the far infrared region
Explanation
In this question angular momentum should be considered as orbital angular momentum not L = nh/2π In s orbital particular value of angular momentum = 0 . Thus option "a" is correct statement Answer: (c)
Q.5
When applied, the uncertainty principle has significance in case of
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a)moving train
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b) spinning cricket ball
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c)moving α -particle
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d)all the above
Explanation
Uncertainty principle is significant only if mass is very very smallAnswer: (c)
Q.6
Which of the following represents de Broglie relation?
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a)
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b)
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c)
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d)
Explanation
Answer: (b)
Q.7
The wave function |ψ2| in Schrodinger wave equation represents
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a) probability of the electron
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b) amplitude of the wave
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c)frequency of the wave
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d)speed of the wave
Explanation
The wave function ψ itself has no physical significance but the square of its absolute magnitude |ψ2| has significance when evaluated at a particular point and at a particular time |ψ2| gives the probability of finding the particle there at that time. Answer:(a)
Q.8
Which of the following statement is not correct?
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a) Angular momentum of 3s electron and 2s electron is equal
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b) Energy level of H-atom are not equally spaced
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c) Energy of electron is zero only when it is stationary
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d) Balmer series lies in visible region
Explanation
Energy of electron is zero at infinite distance Answer: (c)
Q.9
The metal which gives photoelectric effect most easily is
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a)Lithium
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b) Sodium
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c)Calcium
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d)Cesium
Explanation
Cs have lowest ionization energyAnswer: (d)
Q.10
The probability of finding electron in the orbital is
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a) 100%
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b) 90-95%
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c)70-80%
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d)50-60%
Explanation
Answer: (b)
Q.11
The total number of energy orbital's in fifth energy level is
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a) 5
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b) 10
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c)15
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d)25
Explanation
If n is the energy orbit the number of sub shells=n and number of orbits=n2 Answer:(d)
Q.12
The designation of a sub shell with n=4 and l=3 is
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a) 4s
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b) 4p
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c) 4d
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d) 4f
Explanation
l=0 the s l=1 then p l=2 then d l=3 then f Answer: (d)
Q.13
Quantum number not obtained from the solution of Schrodinger wave equation is
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a)Principal quantum number
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b) Azimuthal quantum number
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c)Magnetic quantum number
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d)Spin quantum number
Explanation
Answer: (d)
Q.14
The uncertainty found from the uncertainty principle ( Δx.Δp=h/4π) is
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a) the minimum value
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b) the maximum value
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c)the exact value
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d)only approximate value
Explanation
Answer: (a)
Q.15
Which of the following statement about spectral series is incorrect?
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a) The lines in the Balmer series corresponds to electron transition from energy levels higher than n=2 energy level
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b) Paschen series appears in the infrared region
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c)The lines of Lyman series appears in visible region
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d)Transitions from higher energy level to 4th energy level produce Pfund series which falls in the infrared region
Explanation
Lyman series appears in the ultraviolet region Answer:(c)
Q.16
The dual nature of radiation was proposed by
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a) Max Plank
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b) d-Broglie
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c) Einstein
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d) Schrodinger
Explanation
In 1905, Albert Einstein proposed a radically new picture of electromagnetic radiation (quanta of energy of radiation) to explain photoelectric effect. de-Broglie postulated the wave nature of electrons and suggested that all matter has wave propertiesAnswer: (c)
Q.17
The total number sub shells in N shell is
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a)3
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b) 4
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c)5
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d)7
Explanation
For N shell n=4 thus number of subshell=4Answer: (b)
Q.18
To give a designation to an orbital, we need
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a) Principal and azimuthal quantum number
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b) Principal quantum number and magnetic quantum number
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c)Azimuthal and magnetic quantum number
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d)Principal, azimuthal and magnetic quantum numbers
Explanation
To give exact designation to an orbital, we need n, l and m Answer: (d)
Q.19
The splitting of the spectral lines under the influence of magnetic field is called
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a) Zeeman effect
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b) Compton effect
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c)Photoelectric effect
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d)Diffraction
Explanation
Answer:(a)
Q.20
the correct Schrodinger's wave equation for an electron with E as total energy and V as potential energy is -
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a)
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b)
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c)
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d)
Explanation
Answer: (c)
Q.21
If the threshold frequency of a metal for photoelectric effect is ν0, then which of the following will not happen?
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a)If frequency of the incident radiation is νo, the kinetic energy of the electrons ejected is zero
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b) If the frequency of incident radiation is ν, the kinetic energy energy of the electrons ejected will be hν - hνo
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c)If frequency is kept same at ν but intensity is increased, the number of electrons ejected will increase
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d)If frequency of incident radiation is further increased, the number of photo-electrons ejected will increase
Explanation
Increase in frequency will cause increase in kinetic energy of electron but increase in intensity will increase increase in photoelectronsAnswer: (d)
Q.22
Which of the following transitions of electrons in hydrogen atom will emit maximum energy?
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a) n5 → n4
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b) n4 → n3
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c)n3 → n2
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d)all will emit same energy
Explanation
E3 - E 2 is maximum because as we move out, the energy difference decreasesAnswer: (c)
Q.23
Magnetic quantum number specifies
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a) size of orbitals
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b) Shape of orbitals
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c)Orientation of orbitals in space
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d)Nuclear stability
Explanation
Answer:(c)
Q.24
f uncertainty &deltax in position is along X-axis, then uncertainty Δp in momentum is along
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a) X-axis
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b) Y-axis
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c) X-axis
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d) any axis
Explanation
Answer: (a)
Q.25
The number of orbitals in any shell (n) is equal to
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a)2n2
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b) n2
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c)2n
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d)n
Explanation
Answer: (b)
Q.26
The maximum number of electrons present in any main energy level is given by
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a) (2l + 1)
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b) 2n2
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c)(2n + 1)
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d)n2
Explanation
Answer: (b)
Q.27
With the increasing principal quantum number, the energy difference between adjacent energy levels in H-atom
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a) decreases
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b) increases
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c)remain constant
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d)decreases for lower value of Z and increases for higher value of Z
Explanation
Decreases because E ∝ (1/n2) Answer:(a)
Q.28
The wave-mechanical model of atom is based upon
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a) de Broglie concept of dual character of matter
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b) Heisenberg's uncertainty principle
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c) Schrodinger wave equation
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d) All the three above
Explanation
Answer: (d)
Q.29
Heisenberg's uncertainty principle rules out the exact simultaneous measurement of
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a)probability and velocity
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b) energy and velocity
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c)charge density and radius
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d)position and momentum
Explanation
Answer: (d)
Q.30
in the photo-electric effect, the number of photo-electrons emitted per unit time depends upon the
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a) Energy of incident radiations
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b) Frequency of incident radiations
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c)Intensity of incident radiations
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d)Both frequency and intensity of incident radiation
Explanation
Answer: (c)
Q.31
The radius of nth Bohr's orbit can be obtained from the relation
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a) 0.53n2 nm
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b) 0.53n nm
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c)(0.053/n2) nm
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d)0.053n2 nm
Explanation
Radius of nth Bohr's orbit=0.529n2 Ao=0.0553 n2 Answer:(d)
Q.32
he quantum number which specifies the location as well as energy is
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a) principal quantum number
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b) azimuthal quantum number
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c) spin quantum number
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d) magnetic quantum number
Explanation
Answer: (a)
Q.33
If a light of wavelength λ hits the moving electron, the uncertainty in measurement of its position will be
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a)greater than λ
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b) less than λ
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c)equal to λ
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d)It can have any value
Explanation
uncertainty in position=±λAnswer: (c)
Q.34
he number of electrons subshells in the nth quantum level are
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a) n
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b) 2n2
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c)2n
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d)n-1
Explanation
Subshells in any main level = (Its principal quantum number) = n. For example, for n=2, subshells are 2s and 2p for n=3, subshells are 3s,3p and 3d Answer: (a)
Q.35
According to photo electric effect, the kinetic energy of the ejected electrons is directly proportional to
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a) Wavelength of light
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b) Intensity of light
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c)frequency of light
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d)Velocity of incident light
Explanation
Answer:(c)
Q.36
The angular momentum of an electron in an atomic orbital depends upon
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a) Principal quantum number
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b) azimuthal quantum number
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c)magnetic quantum number
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d)spin quantum number
Explanation
In the process of solving the Schrodinger equation for the hydrogen atom, it is found that the orbital angular momentum is quantized according to the relationship: L2 = l(l+1) ℏ2 Here l is angular momentum quantum nember Answer:(b)
Q.37
The energy of an electron in the third orbit of an atom is -E. the energy of an electron in the first orbit will be
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a) -3E
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b) -E/3
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c) -E/9
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d) -9E
Explanation
En ∝ (1/n2) E1 / E3=32 / 11 ∴ E1=9 × (-E)=-9E Answer: (d)
Q.38
2p - orbital have
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a)n=1, l=2
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b) n=2, l=2
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c)n=2, l=1
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d)n=2, l=0
Explanation
Answer: (c)
Q.39
THe correct order of increasing energies of the orbitals is
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a) 3s, 3p, 3d, 4s, 4p
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b) 3s, 3p, 4s, 4p, 3d
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c) 3s, 3p, 4s, 3d, 4p
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d)3s, 3p, 3d, 4p, 4s
Explanation
follow the rule (n+l),if two orbitals have same (n+l) then higher the value of n higher the energyAnswer: (c)
Q.40
The quantum numbers for the electron present in the valence shell of an element are given below:n=2,l=0, m=0, s=+ 1/the atom is
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a) Lithium
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b) Beryllium
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c)Hydrogen
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d)Boron
Explanation
Electron configuration of valence shell is 2s1.Complete E.C. will be 1s2, 2s1 ∴ Z=3 Answer:(a)
Q.41
ion Q84) The figure given below is representation of the shape of
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a) 3dxy orbital
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b) 3dz2
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c) 2pzorbital
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d) 3dx2-y2 orbital
Explanation
Answer: (d)
Q.42
Consider the electron configuration 1s2 2s2 2px2
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a)It violates Aufbau principle
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b) It violets Hund's rule
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c)It violates Pauli's exclusion principle
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d)It is correct
Explanation
According to Hund's rule 2 electron should be in px and py eachAnswer: (b)
Q.43
The nodes present in 3p-orbital are
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a) one spherical, one planar
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b) two spherical
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c)two planar
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d)one planar
Explanation
number of spherical node=( n-l-1)=(3-1-1)=1there is one planar node in p-orbitalsAnswer: (a)
Q.44
Maximum number of electrons in s, p, d sub-shells are
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a) 2 in each
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b) 2, 4, 6
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c)2,6 ,10
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d)2, 6, 12
Explanation
s do not have any orbital thus 2electronsp have 3 orbitals thus 6electronsd have 5 orbital thus 10 electrons Answer:(c)
Q.45
The value of azimuthal quantum number for electrons present in 4p-orbitals is
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a) 1
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b) 2
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c) 3
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d) 4
Explanation
in 4p, n=3 and l=1 Answer: (a)
Q.46
The 3d-orbitals having electron density in all three axes is
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a)3dxy
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b) 3dz2
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c)3dyz
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d)3dzx
Explanation
Answer: (b)
Q.47
Which of the following has zero electron density in xy plane
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a)dz2
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b) dz2- y2
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c)pz
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d)dxy
Explanation
pz is along z axis hence zero electron density along xy planeAnswer: (c)
Q.48
An electro having an azimuthal quantum number l=3 is
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a) s -electrons
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b) p- electrons
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c)d-electrons
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d)f-electrons
Explanation
Answer:(d)
Q.49
How many electrons in a given atom can have the following set of quantum numbersn=3, l=2, m=+2, s=-1/2
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a) 1
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b) 18
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c) 14
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d) not possible
Explanation
No two electrons in an atom can have same set of quantum numbers Answer: (a)
Q.50
The energy of orbitals of hydrogen atom are in the order
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a)3s < 3p < 4s < 3d < 4p
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b) 3s < 3p < 3d < 4s < 4p
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c)3s=3p=3d < 4s=4p
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d)3s=3p=3d < 4s < 4p
Explanation
in hydrogen, sub-shells of a particular shell are degenerate as it have only one electronAnswer: (c)
0 h : 0 m : 1 s
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