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Physics NEET MCQ
Atom And Nucleus Mcq
Quiz 4
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Q.1
) Electron cannot be constituent of the nucleus because [ AFMC 2010]
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a) the electron is a negatively charged particle
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b) the compton wave length of electron is larger than the size of nucleus
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c) the mass of the electron is very small as compared to the mass of the neutron or proton
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d) None of these
Explanation
Electrons are negatively charged, so if electrons be in nucleus then electron proton can neutraize each other. Answer: (a)
Q.2
) The kinetic energy of an electron which is accelerated through a potential difference of 100V is [ AFMC 2010]
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a)6.626 × 103 watt
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b) 1.16 × 10-34 J
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c)418.6 cal
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d)1.6 × 10-17 J
Explanation
K.E.=q . v=100 × 1.6 ×: 10-19 J =1.6 × 10-17 JAnswer: (d)
Q.3
) A free alpha particle and a free proton, which are seperated by a distance of 10-10 m are released. The K.E. of alpha particle when at infinite seperation is [ AFMC 2007]
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a) 46 × 10-19 J
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b) 23 × 10-19 J
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c)36.8 × 10-19 J
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d) 9.2 × 10-19 J
Explanation
The P.E. of alpha particle due to the proton when they are seperated by 10 -10 m is This P.E. is converted into K.E. ∴ K.E. of alpha particle at infinite distance=46.08 ×: 10-19 JAnswer: (a)
Q.4
) The specific charge of a proton is 9.6 × 107 C/kg . The sepcific charge of a alpha particle will be [ AFMC 2008]
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a) 9.6 × 107 C/kg
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b) 19.2 × 107 C/kg
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c)4.8 × 107 C/kg
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d)2.4 × 107 C/kg
Explanation
Answer:(c)
Q.5
) The working of which of the following is similar to that of a slide projector? [AFMC 2008]
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a) Electron microscope
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b) Scanning electron microscope
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c) Transmission electron microscope
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d) Atomic force microscope
Explanation
Transmission electron microscope works similar to that of a slide projector . Answer: (c)
Q.6
) Which of the following element has highest first ionization potential ? [ AFMC 2009]
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a) As
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b) Bi
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c)Sb
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d)N
Explanation
The valence electrons in nitrogen are bound by a stronger force than that in the case of As, Sb, and Bi. Thus, first ionization potential of nitrogen is the higest among the given elements.Answer: (d)
Q.7
4) Whight light is passed through a dilute solution of potassium permanganate. The spectrum produced by the emergent light is [ AFMC 2008]
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a) band emission spectum
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b) line emssion spectum
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c) band absorption spectrum
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d)line absorption spectrum
Explanation
Answer: (c)
Q.8
) The fussion of 235 U can be triggered by the absorption of a slow netron by a nucleus. Similarily, a slow proton can also be used.This statment is [ AFMC 2007]
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a)correct
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b) wrong
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c)information is insufficient
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d)none of the above.
Explanation
A slow proton cannot tigger a fission in 235U atom. This statment is wrong.Answer: (b)
Q.9
) Activity of radio active sample decreases to (1/3)rd of its original value in 3 days. Then in 9 days its actvity will become [ AFMC 2008]
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a) (1/27) of the original value
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b) (1/9) of the original value
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c)(1/18) of the original value
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d)(1/3) of the original value
Explanation
Intial activity ( i.e., at t=0 )=A 0 Activity after a time t, is A Answer: (a)
Q.10
) A free neutron decays spontaneously into [ AFMC 2008]
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a) a proton, an electron and anti neutrino
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b) a proton, an electron and a neutrino
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c)a proton and electron
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d)a proton, and electron, a neutrino and an anti-neutrino
Explanation
Answer:(a)
Q.11
9) When a sample of solid lithum is placed in a flask of hydrogen gas then following reaction happened This statment is [AFMC 2007]
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a) True
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b) false
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c)may be true for perticular pressure
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d)none of the above
Explanation
Solid litium doesn't fuse with hydrogen gas. For fusion, both should be in gaseous state. So the statement is false. Answer:(b)
Q.12
0) In compound X(n, α ) ----> 3 Li 7 , the element X is [ AFMC 2007]
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a) 2 He 4
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b) 5 B 10
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c) 5 B 9
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d) 4 Be 11
Explanation
Answer: (b)
Q.13
) Order of e/m ratio of proton, α - particle and electron [ AFMC 2004]
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a) (e/m)p >(e/m)α > (e/m)e
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b) (e/m)e > (e/m)p > (e/m)α
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c)(e/m)α > (e/m)e > (e/m)p
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d)none of these
Explanation
Electrical charge on proton, α-particle and electron is e, 2e, e, and mα=4 mp > > me Answer: (b)
Q.14
2) The transition the state n=4 to n=1 in a hydrogen like atom results in ultraviolet radiation. Infrared radition will be obtained in the transition form
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a) 3 → 2
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b) 5 → 4
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c)4 → 2
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d)2 → 1
Explanation
5 →4 transition series of paschen which is fall in infrared region.Answer: (b)
Q.15
3) In Bohr model the hydogen atom, the lowest orbil corresponds to
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a) Intial energy
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b) zero energy
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c) The minimum energy
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d)The maximum energy
Explanation
Answer:(c)
Q.16
) According to Bohr's theory the radius of electon in an orbit described by Principalquantum number n and atomic number Z, is Proportional to.
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a) Z2 n2
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b) n2 / z
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c) Z2 / n
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d) n 2 / Z2
Explanation
Answer: (b)
Q.17
) Number of spectral lines in hydrogen atom is.
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a) 6
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b) 8
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c)15
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d)infinite
Explanation
Answer: (d)
Q.18
) The nucleus which has radius one third of the radius of Cs189 is
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a) Be 9
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b) F19
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c)C12
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d)Li7
Explanation
Answer: (d)
Q.19
7)A nucleus of 210 84 Po originally at rest emits α -particle with speed v what will bethe recoil speed of the daughter nucleus
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a)v / 214
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b) 4v / 214
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c)4v / 206
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d)v / 206
Explanation
According to conservation of momentum, m1 v1=m2 v1=0∴ 4v 1 + 206 v2=0 ∴ v2=-4 v1 / 206 Recoil speed of daughter nucleus is=4v / 206 Answer:(c)
Q.20
) It the radius of a nucleus of mass number 3 is R. then the radius of a nucieus of mass mumber 81 is
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a) 27 R
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b) 9R
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c) 3R
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d) (27)1/2 R
Explanation
Answer: (c)
Q.21
An electron change its Position from orbit n=4 to the orbit n=2 of an atom the wave length of emitted radition in the form of R (where R is Redburg constanst)
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a) 16 / 7R
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b)16 / R
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c)16 / 3R
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d)16 / 5R
Explanation
By using the formula, Answer: (c)
Q.22
0) The control rod in a nuclear reactor is made of
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a) uranium
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b) Cadmium
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c)plutomium
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d)grabhite
Explanation
Answer: (b)
Q.23
1) which of the following isotopes normally fissonable
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a)92 U 233
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b) 92 U 238
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c)92 U 235
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d)92 Np 289
Explanation
Answer:(c)
Q.24
2) The distance of the closest abbroach of an alpha particle fired at a nuclous with kinetic energy K is rThe distemce of the closest approach when thw α- particle is fired at the same nucleus with kinetic energy 2k will be.
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a) r0 / 2
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b) 4 × r0
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c) r0 / 4
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d) 2 × r0
Explanation
At a distance of closest approach kinetic energy of α - particle=Potentical energy of the system. Answer: (a)
Q.25
3) A Free neutron decays into a Proton, an electron and
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a)ν
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b) ν
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c)α
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d)β
Explanation
Answer: (b)
Q.26
4) Which of the following series in the spectrum of hydrogen alone lies in the visible region of the electro magnetic spectrum?
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a) Paschen
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b) Lyman
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c)Brakett
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d) Balmer
Explanation
Answer: (d)
Q.27
5) If 13.6 eV energy is required to ionise the hydrogen atom the energy required to remove the electron form n=2 state is
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a)Zero
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b)10.2 eV
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c)6.8 eV
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d)3.4 eV
Explanation
By using the formula, Inigator potentier for hydrogen En=13.6 / n2 eV Answer:(d)
Q.28
6) It No is the original mass of the substance of halt lift 5 years, the amount of substance left after 15 years is
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a) N0 /16
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b) N0 /8
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c) N0 / 4
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d) N0 / 2
Explanation
by using the formula, Answer: (b)
Q.29
) when U-238 nucleus originallay at rest decay by emitting an α -particle having a speed u the recoil speed of the resi-dual nucleus is.
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a) 4u / 238
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b) -4u / 238
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c)4u / 234
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d)-4u / 234
Explanation
According to conservation of momentumAnswer: (c)
Q.30
8) At a certain instant, a radioactive sample has a decay rate of 5000 dis-interation Per minute. After 5 minute the decay rate is 1250 dis-interations Per minute. Then the decay constant is (Per-min )
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a) 0.2 ln 4
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b) 0.4 ln 4
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c)0.4 ln 2
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d) 0.8 ln 2
Explanation
Answer: (a)
0 h : 0 m : 1 s
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