JEE Questions for Physics Atoms And Nuclei Quiz 24 - MCQExams.com

After two hours, one-sixteenth of the starting amount of a certain radioactive isotope remained undecayed. The half life of the isotope is
  • 15 minutes
  • 30 minutes
  • 45 minutes
  • 1 hour
N atoms of a radioactive element emit n alpha particles per second. The half life of the element is

  • Physics-Atoms and Nuclei-63816.png
  • 2)
    Physics-Atoms and Nuclei-63817.png

  • Physics-Atoms and Nuclei-63818.png

  • Physics-Atoms and Nuclei-63819.png
A radioactive nucleus 92X235 decays to 91Y231. Which of the following particles are emitted
  • One alpha and one electron
  • Two deuterons and one positron
  • One alpha and one proton
  • One proton and four neutrons

Physics-Atoms and Nuclei-63823.png
  • An electron
  • A proton
  • A deuteron
  • An α particle
The rate of disintegration of fixed quantity of a radioactive element can be increased by
  • Increasing the temperature
  • Increasing the pressure
  • Chemical reaction
  • It is not possible
Radon (Rn) decays int o Polonium (Po) by emitting an α– particle with half-life of 4 days. A sample contains 6.4 × 1010 atoms of Rn. After 12 days, the number ofatoms of Rn left in the sample will be
  • 3.2 × 1010
  • 0.53 × 1010
  • 2.1 × 1010
  • 0.8 × 1010
Decay constant of radium is λ. By a suitable process its compound radium bromide is obtained. The decay constant of radium bromide will be
  • λ
  • More than λ
  • Less than λ
  • Zero
In the uranium radioactive series, the initial nucleus is 92U238 and the final nucleus is 82Pb206. When theuranium nucleus decays to lead, the number of α– particles emitted will be
  • 1
  • 2
  • 4
  • 8
The decay constant of a radio isotope is λ. If A1 and A2 are its activities at times t1 and t2 respectively, the number of nuclei which have decayed during the time(t1–t2)
  • A1t1–A2t2
  • A1– A2
  • (A1– A/λ
  • λ (A1– A2)
Which of the following is a correct statement?
  • Beta rays are same as cathode rays
  • Gamma rays are high energy neutrons
  • Alpha particles are singly ionized helium atoms
  • Protons and neutrons have exactly the same mass
Half lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the sample of A and B have equal number of nuclei. After 80 minutes, the ratio of remaining number of A and B nuclei is
  • 1 : 16
  • 4 : 1
  • 1 : 4
  • 1 : 1
A nucleus nXm emits one α and one β particles. The resulting nucleus is
  • nXm–4
  • n–2Xm–4
  • n–4Xm–4
  • n–1Xm–4
In the given nuclear reaction A, B, C, D, E represents

Physics-Atoms and Nuclei-63833.png
  • A = 234, B = 90, C = 234, D = 91, E =β
  • A = 234, B = 90, C = 238, D = 94, E = α
  • A = 238, B = 93, C = 234, D = 91, E = β
  • A = 234, B = 90, C = 234, D = 93, E = α

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  • 2)
    Physics-Atoms and Nuclei-63838.png

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A radioactive sample with a half life of 1 month has the label \ Activity = 2 micro curies on 1.8.1991.\ What will be its activity two months later?
  • 1.0 micro curies
  • 0.5 micro curies
  • 4 micro curies
  • 8 micro curies
Which of the following isotopes is used for the treatment of cancer?
  • K40
  • Co60
  • Sr90
  • I131
If half-life of a radioactive atom is 2.3 days, then its decay constant would be
  • 0.1
  • 0.2
  • 0.3
  • 2.3
A radioactive element 90X238decays into 83Y222. Thenumber of β–particles emitted are
  • 4
  • 6
  • 2
  • 1

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  • 2)
    Physics-Atoms and Nuclei-63849.png

  • Physics-Atoms and Nuclei-63850.png

  • Physics-Atoms and Nuclei-63851.png
A nucleus of an element 84X202 emits anα-particlefirst, a β–particle next and then a gamma photon. The final nucleus formed has an atomic number
  • 200
  • 199
  • 83
  • 198
A certain radioactive material ZXA starts emitting α and β particles successively such that the end product is Z–3YA–8. The number of α and β particles emitted are
  • 4 and 3 respectively
  • 2 and 1 respectively
  • 3 and 4 respectively
  • 3 and 8 respectively
A radioactive substance has a half-life of 1 year. The fraction of this material, that would remain after5 years will be

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  • 2)
    Physics-Atoms and Nuclei-63857.png

  • Physics-Atoms and Nuclei-63858.png

  • Physics-Atoms and Nuclei-63859.png
If half-life of a substance is 3.8 days and its quantity is 10.38 g. Then substance quantity remaining left after19 days will be
  • 0.151 g
  • 0.32 g
  • 1.51 g
  • 0.16 g
After five half lives what will be the fraction of initial substance

  • Physics-Atoms and Nuclei-63862.png
  • 2)
    Physics-Atoms and Nuclei-63863.png

  • Physics-Atoms and Nuclei-63864.png

  • Physics-Atoms and Nuclei-63865.png
Which is the correct expression for half-life?

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  • 2)
    Physics-Atoms and Nuclei-63868.png

  • Physics-Atoms and Nuclei-63869.png

  • Physics-Atoms and Nuclei-63870.png
The activity of a radioactive sample is 1.6 curie and its half-life is 2.5 days. Its activity after 10 days will be
  • 0.8 curie
  • 0.4 curie
  • 0.1 curie
  • 0.16 curie
In a mean life of a radioactive sample
  • About 1/3 of substance disintegrates
  • About 2/3 of the substance disintegrates
  • About 90% of the substance disintegrates
  • Almost all the substance disintegrates
During mean life of a radioactive element, the fraction that disintegrates is
  • e
  • 2)
    Physics-Atoms and Nuclei-63874.png

  • Physics-Atoms and Nuclei-63875.png

  • Physics-Atoms and Nuclei-63876.png
When a radioactive substance emits an α–particle, its position in the periodic table is lowered by
  • One place
  • Two places
  • Three places
  • Four places

Physics-Atoms and Nuclei-63879.png
  • 10 days
  • 20 days
  • 40 days
  • None of these
A radioactive nucleus with Z protons and N neutrons emits anα–particle, 2beta–particles and 2 gamma rays. The number of protons and neutrons in the nucleus leftafter the decay respectively, are
  • Z – 3, N –1
  • Z – 2, N –2
  • Z – 1, N –3
  • Z, N –4
Certain radio-active substances reduces to 25% of itsvalue in 16 days. Its half-life is
  • 32 days
  • 8 days
  • 64 days
  • 28 days

Physics-Atoms and Nuclei-63884.png
  • 92, 236
  • 88, 230
  • 90, 234
  • 91, 234
The half-life of a radioactive substance against α–decay is 1.2 × 107 s. What is the decay rate for 4 × 1015 atomsof the substance
  • 4.6 × 1012 atoms/s
  • 2.3 × 1011 atoms/s
  • 4.6 × 1010 atoms/s
  • 2.3 × 108 atoms/s
A radioactive material has an initial amount 16 g. After 120 days it reduces to 1 g, then the half-life of radioactive material is
  • 60 days
  • 30 days
  • 40 days
  • 240 days

Physics-Atoms and Nuclei-63888.png
  • β–emission
  • α–emission
  • e–capture
  • Fission

Physics-Atoms and Nuclei-63889.png

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    Physics-Atoms and Nuclei-63891.png

  • Physics-Atoms and Nuclei-63892.png

  • Physics-Atoms and Nuclei-63893.png
If 92U238undergoes successively 8 α–decays and time6 β–decays, then resulting nucleus is
  • 82U206
  • 82Pb206
  • 82U210
  • 82U214
The activity of a sample of a radioactive material is A at time t1 and A2 at time t2(t2> t1). If its mean life is T, then
  • A1t1 = A2t2
  • A1 – A2 = t2 – t1
  • A2 = A1e(t1–t2)/T
  • A2 = A1e(t1–t2)T

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    Physics-Atoms and Nuclei-63899.png

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Which of the following rays are not electromagnetic waves?
  • γ–rays
  • β–rays
  • Heat rays
  • X-rays
A sample of radioactive element has a mass of 10 g at an instant t = 0. The approximate mass of this element inthe sample after two mean lives is
  • 2.50 g
  • 3.70 g
  • 6.30 g
  • 1.35 g
Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called
  • Gamma camera
  • CAT scan
  • Radiotracer technique
  • Gamma ray spectroscopy
A radioactive decay chain starts from 93Np237 and produces 90Th229by successive emissions. The emitted particles can be
  • Two α–particles and one β–particle
  • Three β+ particles
  • One α particle and two β+ particles
  • One α–particle and two β– particles
The half-life of sample of a radioactive substance is 1 hour. If 8 × 1010 atoms are present at t = 0, then thenumber of atoms decayed in the duration t = 2 hour tot = 4 hour will be
  • 2 × 1010
  • 1.5 × 1010
  • Zero
  • Infinity
Carbon dating is best suited for determining the age of fossils if their age in years is of the order of
  • 103
  • 104
  • 105
  • 106
The half-life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after
  • 2400 years
  • 3200 years
  • 4800 years
  • 6400 years
The half-life of a radioactive substance is 40 years. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant
  • 40 year, 0.9173/year
  • 90 year, 9.017/year
  • 80 year, 0.0173 year
  • None of these
The half-life of a radioactive substance is 3.6 days. How much of 20 mg of this radioactive substance will remain after 36 days
  • 0.0019 mg
  • 1.019 mg
  • 1.109 mg
  • 0.019 mg
A radioactive material has a half life of 10 days. What fraction of the material would remain after 30 days
  • 0.5
  • 0.25
  • 0.125
  • 0.33
0:0:1


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