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NEET Chemistry MCQ
Structure Of Atom Mcq Neet Chemistry
Quiz 7
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Q.1
MAximum number of electrons present in 'N' shell .... [ EAMCET 1984]
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a)18
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b) 32
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c)2
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d)8
Explanation
For shell 'N'; n=4 number of electrons=2n2=2 &time s 42=32 Answer: (b)
Q.2
When alpha particles are sent through a thin metal foil, most of them go straight through the foil because ... [ IIT 1994]
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a) alpha particles are mush heavier than electron
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b) alpha particles are positive charged
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c)alpha particles move with high velocity
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d)most part of atom is empty
Explanation
Answer: (d)
Q.3
Which of the following is not correct for electronic distribution in the ground state [ AIIMS 1982]
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a)
0%
b)
0%
c)
0%
d)
Explanation
Cu is 3d10 4s1 not 3d9 4s2 Answer:(c)
Q.4
the ratio of the difference in energy between the first and the second Bohr orbit to that between the second and the third Bohr orbit is [ NCERT1980]
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a) 1:2
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b) 1:3
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c) 4:9
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d) 27:5
Explanation
Energy of nth orbit ∝ 1/ n2 Thus E1=C/(1) second orbit E2=C/(2)2=C/(4)third orbit energy E3=C/(3)2=C/(9) Difference E1 - E2=C (3/4) Difference E2 - E3=C (5/36) Thus ratio=3/4 ÷ 5/36=27/5Answer: (d)
Q.5
The volume of nucleus is about [ eamcet 1986]
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a)10-15 times that of atom
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b) 10-10 times that of atom
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c)10-15 times that of atom
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d)10-20 times that of atom
Explanation
Answer: (c)
Q.6
Which one of the following sets of quantum numbers represents an impossible arrangement? [ IIT 1986]
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a) n=3, l=2, ml=-2, ms=1/2
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b) n=4, l=0, ml=0, ms=1/2
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c)n=3, l=2, ml=-2, ms=1/2
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d)n=5, l=3, ml=0, ms=1/2
Explanation
Option 'c' since 'm' can take the values from -l to +l Answer: (c)
Q.7
Remaining part of atom except outer orbit is called [ CPMT 1982]
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a)Kernel
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b) Core
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c)Empty space
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d)None
Explanation
Answer:(a)
Q.8
How many unpaired electrons are there in NI2+ [ IIT 1981]
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a) 0
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b) 2
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c) 4
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d) 8
Explanation
Answer: (b)
Q.9
Which quantum number is sufficient to describe the electron in hydrogen atom .... [ CPMT 1984]
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a)l
0%
b) n
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c)m
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d)s
Explanation
Hydrogen have only one electron thus n is sufficientAnswer: (b)
Q.10
The symbol of the element whose atoms have the outer most electronic configuration 2s2, 2p3 is ... [ EAMCET 1983]
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a) N
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b) Li
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c)P
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d)Na
Explanation
Answer: (a)
Q.11
The maximum number of electrons in p-orbital with n=0 and m=0 is [ EAMCET 1981]
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a) 2
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b) 6
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c)10
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d)14
Explanation
Answer:(a)
Q.12
The ratio of the radii of the first three Bohr orbits is [ NCERT 1980]
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a) 1:0.5:0.33
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b) 1:2:3
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c) 1:4:9
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d) 1:8:27
Explanation
rn ∝ n2 Answer: (c)
Q.13
The atomic weight of an element is 23 and atomic number isThe number of protons, electrons and neutrons respectively present in the atom of the element are [ AFMC 89]
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a)11, 11, 12
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b) 12, 12, 11
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c)11,12, 11
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d)12,11,12
Explanation
Answer: (a)
Q.14
The number of unpaired electrons in Cr+3 ( atomic number 24) is [ MLNR 1986]
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a) 6
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b) 4
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c)3
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d)1
Explanation
Cr=[Ar] 3d5 4s1,/ Cr+3=[Ar] 3d3Answer: (c)
Q.15
Cathode rays are deflected by ..... [ CPMT 1982]
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a) an electric filed only
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b) a magnetic field only
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c)by both
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d)by none
Explanation
Answer:(c)
Q.16
Rutherford's experiment on scattering of particles showed for the first time that the atom has [ IIT1981]
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a) Electrons
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b) Protons
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c) Nucleus
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d) Neutrons
Explanation
Answer: (c)
Q.17
As we move away from nucleus, the energy of orbit .... [ DPMT 1984]
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a)Decreases
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b) Increases
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c)remains uncharged
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d)none of these
Explanation
Electron near nucleus have binding energy which is shown negative and at infinity energy of electron is zero. Thus increasesAnswer: (b)
Q.18
The spectrum of He is expected to be similar to that of [ AIIMS 1980]
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a) H
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b) L+
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c)Na
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d)He+
Explanation
Li+ number of electrons are 2, same number of electrons are in He Answer:(b)
Q.19
The value of Plank's constant is .... [ EAMCET 1983]
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a) 6.6256 ×10-27 erg sec
0%
b) 66.256 × 10-27 erg sec
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c) 6.02 ×10-15 erg
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d) 3.01 ×10-23 erg
Explanation
Answer: (a)
Q.20
The triad of nuclei which is isotonic is ... [ IIT 1988]
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a)6C14, 7N15, 9F17
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b)6C12, 7N14, 9F19
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c)6C14, 7N14, 9F17
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d)6C14, 7N14, 9F19
Explanation
Isotonic means number of neutrons sameAnswer: (a)
Q.21
The number of spherical nodes in 3p orbitals are ... [ CBSE PMT 1988]
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a) one
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b) three
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c)two
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d)four
Explanation
number of spherical node=(n- l -1) here n=3 and l=1 number of spherical nodes=(3-1-1)=1Answer: (a)
Q.22
The radius of second Bohr's orbital is ... [ BHU 1989]
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a) 0.053nm
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b) 0.0534/4 nm
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c)0.053 ×4 nm
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d)0.053 ×20 nm
Explanation
rn=0.053n2r<2=0.053 × (2)2 Answer:(c)
Q.23
If the mass number of an element is W and its atomic number is N, then [ CPMT 1989]
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a) Number of e-1=W-N
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b) Number of 1H1=W -N
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c) Number of 0n=W -N
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d) Number of 0n1=N
Explanation
Number of neutron=A - Z=W - N Answer: (c)
Q.24
Number of electrons in the outermost orbit of the element of atomic number 15 is ... [ CPMT 1988]
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a)7
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b) 5
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c)3
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d)2
Explanation
P=2,8,5Answer: (b)
Q.25
The maximum number of electrons in a subshell is given by the expression [ CBSE PMT 1989]
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a) 4l-2
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b) 4l+2
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c)2l+1
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d)2n2
Explanation
number of orbitals in sub shell=(2l+1) ∴ number of electrons=2(2l+1)=4l+2Answer: (b)
Q.26
An orbit with quantum number n=4 , l=3, m=0, and s=-(1/2) is called [ Pb. CET sample paper 1990]
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a) 3s orbital
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b) 3p orbital
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c)4d orbital
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d)4f orbital
Explanation
Answer:(d)
Q.27
Which of the following is correct in case of p-orbitals? [ EAMCET 1990]
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a) They are spherical
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b) They have strong directional character
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c) They have no directional character
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d) They are five fold degenerate
Explanation
Answer: (b)
Q.28
If r is the radius of first orbit, the radius of nth orbit of H-atom is given by .... [ CBSE PMT 1988]
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a)rn2
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b) rn
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c)r/n
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d)r2n2
Explanation
radius rn ∝ n2Answer: (a)
Q.29
Indicate which electronic configuration amongst the following correctly represents sulphur atom [ BIT Ranchi 1989]
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a) 1s2 2s2 2p6 3s2 3p2 3d2
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b)1s2 2s2 2p6 3s2 3p2 4s2
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c)1s2 2s2 2p6 3s2 3p6 4s14p1
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d)1s2 2s2 2p6 3s2 3p4
Explanation
sulphur S atomic number 16, option 'd' is correct according to Aufbau ruleAnswer: (d)
Q.30
If the speed of electron in the Bohr's first orbit of hydrogen atom be x, then speed of the electron in the 3rd orbit is .... [ IIT 1990]
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a) x/9
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b) x/3
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c)3x
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d)9x
Explanation
velocity of electron in orbit ∝ (1/n) Answer:(b)
Q.31
Spectrum produced due to transition of an electron from M to L shell is ... [ AFMC 1990]
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a) absorption
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b) emission
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c) X-ray
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d) continuous
Explanation
since electron moved from higher energy to lower energy orbit spectra is emission Answer: (b)
Q.32
The orbital diagram in which aufbau principle is violated is
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a)
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b)
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c)
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d)
Explanation
s orbital should be filled first before p orbitalAnswer: (b)
Q.33
Number of electrons in -CONH2 is .. [ AMU 1988]
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a) 22
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b) 24
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c)20
0%
d)28
Explanation
number of electrons C=6, O=8, N=7, H2=2 total electron=23 one electron from other atom to form a covalent compound thus number of electrons=23 + 1=24Answer: (b)
Q.34
In a set of degenerate orbitals, the electron distribute themselves to retain like spins as far as possible. This statement is attributed to [ Pb. CET 1989]
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a) Pauli exclusion principle
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b) Aufbau principle
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c)Hand's rule of maximum multiplicity
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d)Slater rules
Explanation
Answer:(c)
Q.35
Which of the following statements concerning the four quantum numbers is false [ Pb. CET 1990]
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a) n gives idea of the size of an orbital
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b) l gives the shape of an orbital
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c) m gives the energy of the electron in the orbital
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d) s gives the direction of spin of the electron in the s-orbit
Explanation
m gives spatial orientation Answer: (c)
Q.36
The electron in K-shell of the atom will differ in ....{MLNR 1988]
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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
for K-shell n=1 and l=0 thus only spin quantum numbers differAnswer: (d)
Q.37
An ion has 18 electrons in the outermost shell, it is ... [CBSE PMT 1990]
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a) Cu+
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b) Th4+
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c)Cs+
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d)K+
Explanation
Electron configuration of Cu+=[Ne]3s2 3p6 3d10Answer: (a)
Q.38
If the atomic number of nickel and copper are 28 and 29 respectively, which of the following does the electric configuration 1s2 2s2 2p6 3s2 3p6 3d10 represent [ Pb. CET 1988]
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a)Cu+
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b) Cu2+
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c)Ni2+
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d)Ni
Explanation
Answer:(a)
Q.39
Which of the following statement does not form a part of Bohr's model of hydrogen atom [ CBSE PMT 1989]
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a) Energy of the electrons in the orbits is quantized
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b) The electron in the orbit nearest the nucleus has lower energy
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c) Electrons revolve in different orbits around the nucleus
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d) The position and velocity of the electrons in the orbit cannot be determined simultaneously
Explanation
option 'd' is uncertainty principle Answer: (d)
Q.40
The size of nucleus is measured in ....[EAMCET 1988]
0%
a)amu
0%
b) Angstrom
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c)Fermi
0%
d)cm
Explanation
Answer: (c)
Q.41
Which of the sets of quantum numbers is impossible? [ Pb.CET 1989]
0%
a) n=3, l=0, m=-1
0%
b) n=3, l=2, m=+1
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c)n=3, l=1 m=-1
0%
d)n=3, l=2,m=0
Explanation
If l=0 then m=0Answer: (a)
Q.42
How many spherical nodes are present in 4s orbital in hydrogen atom? [ Pb. CET 1990]
0%
a) 0
0%
b) 1
0%
c)2
0%
d)3
Explanation
Spherical nodes in s orbital=(n-1)=4-1=3 Answer:(d)
Q.43
The ratio between the neutrons in C and Si with respect to atomic masses 12 and 28 is .... [ EAMCET 1990]
0%
a) 2:3
0%
b) 3:2
0%
c) 3:7
0%
d) 7:3
Explanation
Neutrons in C=6, and neutron is Si=14 Ratio 6:14=3:7 Answer: (c)
Q.44
When the value of the azimuthal quantum number is 3, the magnetic quantum number can have values [ MP PMT 1987]
0%
a)+1, -1
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b) +1, 0, -1
0%
c)+2, +1, 0, -1, -2
0%
d)+3, +2, +1, 0, -1, -2, -3
Explanation
Answer: (d)
Q.45
Mass of the neutron is of the order of ... [ MLNR 1988]
0%
a) 10-23 kg
0%
b) 10-24 kg
0%
c)10-26 kg
0%
d)10-27 kg
Explanation
Answer: (d)
Q.46
If electron has spin quantum number of +1/2 and magnetic quantum number -1, it cannot be present in [ CBSE PMT 1989]
0%
a) d-orbital
0%
b) f-orbital
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c)p-orbital
0%
d)s-orbital
Explanation
for m=-1 , l must be 1, but for s-orbital l=0 Answer:(d)
Q.47
The magnetic quantum number represents...... [ MLNR 1990]
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a) size of the orbital
0%
b) spin angular momentum
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c) orbital angular momentum
0%
d) spatial orientation of orbital
Explanation
Answer: (d)
Q.48
The total spin resulting from a d7 configuration is .... [ Pb CET 1989]
0%
a)3/2
0%
b) 1/2
0%
c)2
0%
d)1
Explanation
Unpaired electrons with parallel spin=3 Thus 3 ×(1/2)=3/2Answer: (a)
Q.49
The correct set of quantum number for the unpaired electron of chlorine atom is [ JIPMER 1994]
0%
a) n=2, l=1, m=0
0%
b) n=2, l=1, m=1
0%
c)n=3, l=1, m=-1
0%
d)n=3, l=0, m=0
Explanation
Unpaired electron of Cl is 3px1 n=3, l=1, m=-1,0,+1Answer: (c)
Q.50
on Q351) The energy of an orbit in hydrogen atom is given by the relationWhich of the following properties represents the constant in the above relation? [Pb CET 1990]
0%
a) Electron affinity
0%
b) Ionization energy
0%
c)Electronegativity
0%
d)Bond energy
Explanation
Equation states amount of energy required to take electron to infinity Answer:(b)
0 h : 0 m : 1 s
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