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NEET Chemistry MCQ
Structure Of Atom Mcq Neet Chemistry
Quiz 8
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Q.1
the spectrum of He+ is expected to be similar to that of .... [ AIITMS 1990]
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a) Hydrogen
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b) Li+
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c) Na
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d) He
Explanation
Answer: (a)
Q.2
Magnetic quantum number for the valence electron in sodium atom is equal to.... [ CPMT 1988]
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a)3
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b) 2
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c)1
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d)0
Explanation
Last electron is 3s1 hence l=0, m=0Answer: (d)
Q.3
Number of unpaired electrons in N2+ is ..[ CBSE PMT 1989]
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a) 2
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b) 0
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c)1
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d)3
Explanation
N2+=1s2 2s2, 3p1Answer: (c)
Q.4
p orbital can accommodate .... [ MLNR 1990]
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a) 4 electrons
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b) 6 electrons
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c)2 electrons with parallel spin
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d)2 electrons with opposite spin
Explanation
given is p-orbital not orbit, any orbital can accommodate only two electrons with opposite spin Answer:(d)
Q.5
The atomic weight of an atom is due to... [ AFMC 1990]
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a) Electrons and protons
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b) Electrons and neutrons
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c) Neutron and protons
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d) Electron, neutron and protons
Explanation
Answer: (d)
Q.6
For a dumbell shaped orbital, the value of l is ... [ CPMT 1987]
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a)0
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b) l
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c)+1 or -1
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d)3
Explanation
Answer: (b)
Q.7
Which of the following is the smallest in size [ IIT 1989]
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a) N3-
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b) O2-
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c)F-
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d)Na+
Explanation
Number of electrons are same in all but nuclear charge is maximum on Na+Answer: (d)
Q.8
the total number of electrons that can be accommodated in all the orbitals having principal quantum number 2 and Azimuthal quantum number 1 ... [ CPMT 1989]
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a) 2
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b) 4
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c)6
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d)8
Explanation
when l=1 then m can take 3 values thus 6 electrons Answer:(c)
Q.9
The energy of an electron in the nth Bohr orbit of hydrogen atom is ...{CBSE PMT 1992]
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a) 13.6/n4 eV
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b) 13.6/n3 eV
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c)13.6/n2 eV
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d)13.6/n eV
Explanation
Answer: (c)
Q.10
According to Bohr's theory, the angular momentum for an electron in 5th orbit is ...[BHU 1992]
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a) 2.5h /π
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b) 5h/π
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c)25h/π
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d)5π/2π
Explanation
Angular momentum=nh/2π Answer:(a)
Q.11
Which of the statements is incorrect for an electron that has the quantum number n=4 and m=2? [ MLNR 1993] when m=2, then l can not be0 or 1 Answer: (d)
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a) The electron may have the quantum number s=+1/2
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b) The electron may have the quantum number l=2
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c) The electron may have the quantum number m=-2
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d) The electron may have the quantum numbers l=0, 1, 2
Explanation
when m=2, then l can not be0 or 1 Answer: (d)
Q.12
Pick out the isoelectronic structures from the following I) CH3+II) H3O+III) NH3IV) CH3- [ IIT 1993
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a) I and II
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b) III and IV
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c)I and III
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d)II, III and IV
Explanation
Number of electrons in each caseCH3+=6 + 3 -1=8H3O+=3 + 8 -1=10NH3=7 + 3=10CH3-=6 + 3 +1=10Answer: (d)
Q.13
Which of the following pair has same electronic structure? [ CPMT 1992]
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a) Ca, Ar
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b) Mg, Na+
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c)Ag, Sn
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d)Ar, Cl-
Explanation
Answer:(d)
Q.14
The quantum numbers for the designation of 3d are ... [ Pb CET 1991]
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a) n=3, m=-3
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b) n=3, l=3
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c) n=4, l=1
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d) n=3, l=2
Explanation
Answer: (d)
Q.15
The atomic number of an element having the valence shell electronic configuration 4s2 4p6 is ... [ PMPMT 1991]
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a)35
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b) 36
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c)37
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d)38
Explanation
According to Aufbau : [Ne] 4s2, 3d10 4p6 total number of electrons=18+18=36 Number of electrons=number of protons Atomic number=number of protons=36Answer: (b)
Q.16
The maximum number of electrons in all those orbitals for which principal quantum number is 3 and azimuthal quantum number 2 is
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a) 2
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b) 8
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c)10
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d)18
Explanation
For l=2 number of orbitals are 5 thus number of electrons=10Answer: (c)
Q.17
Which of the following represents the correct set of quantum numbers of a 4d electron? [ MLNR1992]
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a) 4, 3, 2, +1/2
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b) 4, 2, -2, 0
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c)4, 3, -2, +1/2
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d)4, 2, 1, -1/2
Explanation
for d orbital l=2 and s=± 1/2 Answer:(d)
Q.18
What is different in isotopes of an element?
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a) Atomic number
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b) Mass number
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c) Number of protons
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d) Number of electrons
Explanation
Number of neutrons in isotopes are different but number of protons are same Mass number=no. of neutrons + no. of protons Answer: (b)
Q.19
In any sub-shell, the maximum number of electrons having same value of spin quantum number is
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a)
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b) l + 2
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c) 2l + 1
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d) 4l + 2
Explanation
Total number of electron in subshell = 2(2l + 1); l = angular quantum number ∴ maximum number of electrons having same value of spin quantum number = 2l+1 Answer:(c)
Q.20
The orbital diagram in which both Pauli's exclusion principle and Hund's rule are violated is ... [ BIT 1992]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
in option 'a' , in px orbital both electrons are parallel, violation of Pauli's exclusion principle and Px two electrons and pz is vacant , violation of Hund's ruleAnswer: (a)
Q.21
Which of the following is violation of Pauli's exclusion principle? [ IIT 1993]
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a)
0%
b)
0%
c)
0%
d)
Explanation
in option 'b' , s orbit electrons with parallel spin Answer:(b)
Q.22
Which of the following sets of quantum numbers represents an impossible arrangement? [ Pb CET 1991]
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a) n=3, l=2, m=-2, s=1/2
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b) n=4, l=0, m=0, s=1/2
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c) n=3, l=2, m=-3, s=1/2
0%
d) n=5, l=3, m=0, s=1/2
Explanation
If l=2 the m=-2,-1,0,+1 or +2 Answer: (c)
Q.23
How many electrons can have value n=2, l=1, and s=+1/2 in the configuration 1s2 2s2 2p3 [ MLNR 1992]
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a)1
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b) 3
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c)5
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d)7
Explanation
when l=1 then there are there orbitals, each orbital can have one electron with s=+1/2 Thus 3 electronsAnswer: (b)
Q.24
The de Broglie equation suggest that an electron has .... [ BHU 1992]
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a) Particle nature
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b) Wave nature
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c)Particle - wave nature
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d)Radiation behavior
Explanation
Answer: (c)
Q.25
the number of unpaired electrons in the p-subshell oxygen atom is .... [ Hariyana CEET 1991]
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a) 3
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b) 2
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c)1
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d)4
Explanation
O=1s2, 2s2 , 2p4Thus unaired electrons two Answer:(b)
Q.26
The value of azimuthal quantum number l=2 represents... [BHU 1993]
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a) s -orbital
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b) p -orbital
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c) d -orbital
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d) f -orbital
Explanation
Answer: (c)
Q.27
Which combinations of quantum numbers n, l, m and s for the electron in an atom does not provide a permissible solution of the wave equation? [ IIT 1992]
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a)3,2,-2, 1/2
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b) 3, 3, 1, -1/2
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c)3, 2, 1, 1/2
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d)3, 1, 1, -1/2
Explanation
If n=3 then maximum value of l=2Answer: (b)
Q.28
The probability of finding an electron residing in a px orbit is zero [ AIIMS 1991]
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a) in yz plane
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b) in the xy plane
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c)in the y-direction
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d)in the z-direction
Explanation
Answer: (a)
Q.29
For an electron if the uncertainty is velocity is Δv the uncertainty in its position (Δx) is given bt ... [ AIIMS 1994]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
According to Uncertainty principle Answer:(c)
Q.30
Energy of third orbit of Bohr's atom is ...[PMT 1991]
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a) -13.6 eV
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b) -3.4 eV
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c) -1.5 eV
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d) None of these
Explanation
Energy of nth orbit=-13.6/n2=-13.6/(3)2=-1.51 eV Answer: (c)
Q.31
The electronic configuration of the element which is just above the element with atomic number 43 in the same periodic group is ... [ MLNR 1992]
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a)1s2 2s2 2p6 3s2 3p6 3d5 4s2
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b) 1s2 2s2 2p6 3d2 3p6 3d10
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c)1s2 2s2 2p6 3d2 3p6 3d64s1
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d)1s2 2s2 2p6 3d2 3p6 3d10 1s1 4p6
Explanation
Z=43 -18=25Answer: (a)
Q.32
The electron in an atom{Bihar CEE 1992]
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a) moves randomly around the nucleus
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b) has fixed space around the nucleus
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c)is stationary in various energy levels
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d)moves around its nucleus in definite energy level
Explanation
option "d" is correct according to Bohr theoryAnswer: (d)
Q.33
If electron, hydrogen, helium and neon nuclei are all moving with the velocity of light, then the wavelengths associated with these articles are in order
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a) electron > hydrogen > helium >neon
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b) electron > helium &hydrogen > neon
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c)electron < hydrogen
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d)neon < hydrogen < helium ≤electron
Explanation
wave length λ ∝ (1/m) Answer:(a)
Q.34
The value of Plank's constant is .... [ Harayana CET 1991]
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a) 6.6 ×10-32 g m2 sec
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b) 6.6 ×10-34 kg m2 sec-1
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c) 6.6 ×10-33 kg m2 sec-1
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d) 6.6 ×10-34 g m2 sec-1
Explanation
Answer: (b)
Q.35
Which of the following relates to photos both as wave motion and as a stream of particles{IIT 1992]
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a)Interference
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b) E=mc2
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c)Diffraction
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d)E=hν
Explanation
Interference and Diffraction is related to wave only. Answer: (c)
Q.36
The number of d electrons in Fe2+ ( at.no of Fe=26) is not equal to that of the .....[ MLNR 1993]
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a) p-electrons in Ne( at. no 10)
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b) s- electrons in Mg (at. no.=12)
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c)d electrons in Fe
0%
d)p electrons in Cl-
Explanation
Number of d electrons : E.C. of Fe=[ Ar] 3d5, E.C of Fe2+=[ Ar] 3d6, 4s2 Number of d electrons==6 Cl=[NE] 3s2, 3p5 number of p electrons=6 Cl-=[Ne] 3s2 3p6 number of p electrons=6Answer: (d)
Q.37
The electronic configuration of Cu ( atomic number 29) is
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a) 1s2 2s2, 2p6, 3s2, 3p6, 4s2, 3d9
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b) 1s2 2s2, 2p6, 3s2, 3p6, 3d10 4s2,
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c) 1s2 2s2, 2p6, 3s2, 3p6, 4s2,4p6,5s2, 5p1
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d)1s2 2s2, 2p6, 3s2, 3p6, 4s2 4p6 3d3
Explanation
Answer:(b)
Q.38
Which of the following is never true for cathode rays? [ CBSE PMT 1994]
0%
a) They posses kinetic energy
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b) They are electromagnetic waves
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c) They produce heat
0%
d) They produce mechanical pressure
Explanation
Answer: (b)
Q.39
The number of electrons in 3d shell for element with atomic number 26 is [ Hariyana CEET]
0%
a)4
0%
b) 6
0%
c)8
0%
d)10
Explanation
Z=26 EC=[Ar] 4s2, 3d6Answer: (b)
Q.40
Which of the following pairs are isobars? [ KECT 1992]
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a) 92U235 , 94Pu239
0%
b) 36Kr83 , 36Kr84
0%
c)10Ne19 , 9F19
0%
d)58Ce139 , 58Ce140
Explanation
Isobars have same number of neutronsAnswer: (c)
Q.41
When the azimuthal quantum number has a value of l=1, the shape of the orbital is [ MP PRT 1993]
0%
a) Unsymmetrical
0%
b) Spherically symmetrical
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c)Dumb-bell
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d)Complicated
Explanation
Answer:(c)
Q.42
Total possible values for magnetic quantum number for the values of l=3 is ..... [ Haryana CET 1991]
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a) 3
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b) 1
0%
c) 5
0%
d) 7
Explanation
for l possible number of values are ( 2l+1) Answer: (d)
Q.43
The order of filling of electrons in the orbital's of an atom will be [ CBSE PMT 1991]
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a)3d, 4s, 4p, 4d, 5s
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b) 4s, 3d, 4p, 5s, 4d
0%
c)5s, 4p, 3d, 4d, 5s
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d)3d, 4p, 4s, 4d, 5s
Explanation
Answer: (b)
Q.44
Which of the following series of lines is found in UV region of the atomic spectrum of hydrogen/ [ EAMCET 1991]
0%
a) Balmar series
0%
b) Paschen series
0%
c)Brackett series
0%
d)Lyman series
Explanation
Answer: (d)
Q.45
6C 14 and 7 N 14 may be classified as .. [ Pb CET sample paper 1993]
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a) Isotopes
0%
b) Isotones
0%
c)Isobars
0%
d)Isoelectronic
Explanation
Both have same mass number hence isobar Answer:(c)
Q.46
The electron was shown experimentally to have wave properties by ... [ CBSE PMT 1994]
0%
a) de Broglie
0%
b) Davisson and Germer
0%
c) N. Bohr
0%
d) Schrodinger
Explanation
Answer: (b)
Q.47
If the radius of first Bohr's orbit be ao, then the radius of the third orbit would be [ MP PMT 1998]
0%
a)3 ×ao
0%
b) 6 ×ao
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c)9 ×ao
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d)(1/9) ×ao
Explanation
Radius of nth orbit=ao ×n2Answer: (c)
Q.48
Number of protons, neutrons and electrons in the element 89X231 is ...{AFMC 1997]
0%
a) 89, 89, 242
0%
b) 89, 142, 89
0%
c)89, 71, 89
0%
d)89, 231, 89
Explanation
Answer: (b)
Q.49
The radius of the atom is of the order of ... [ MP PMT 1995]
0%
a) 10-10 cm
0%
b) 10-13 cm
0%
c)10-15 cm
0%
d)10-8 cm
Explanation
Answer:(d)
Q.50
Bohr's model of atom conflict with ... [ DPMT 1994]
0%
a) Pauli's exclusion principle
0%
b) Heisenberg's uncertainty principle
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c) max plank's quantum theory
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d) all above three
Explanation
Bohr's atomic model give definite distance and position of electron in orbit Answer: (b)
0 h : 0 m : 1 s
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