3 . 7 × 10 10 disintegrations/sec

3 . 7 × 10 7 disintegrations/sec

Physics - Nuclei - Quiz-10

The activity of a sample is $64 \times 10^{- 5}$ Ci. Its half-life is 3 days. The activity will become $5 \times 10^{- 6}$ Ci after

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12 days
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7 days
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18 days
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21 days

The half-life of radon is 3.8 days. Three forth of a radon sample decay in

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5.02 days
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15.2 days
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7.6 days
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11.4 days

A nucleus of an element ${}_{84}^{202}X$ emits an $α$ -particle first, a $β$ -particle next and then a gamma photon. The final nucleus formed has an atomic number

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200
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199
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83
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198

Plutonium decays with a half-life of 24000 years. If the plutonium is stored for 72000 years, then the fraction of plutonium that remains is

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$\frac{1}{2}$
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$\frac{1}{3}$
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$\frac{1}{4}$
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$\frac{1}{8}$

A radioactive substance emits

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$α$ -rays
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$β$ -rays
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$γ$ -rays
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All of these

The large scale destruction, that would be caused due to the use of nuclear weapons is called

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Nuclear holocaust
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Thermo-nuclear reaction
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Nuetron reproduction factor
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None of these

A radioactive substance has a half-life of 1 year. The fraction of this material, that would remain after 5 years will be

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$\frac{1}{32}$
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$\frac{1}{5}$
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$\frac{1}{2}$
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$\frac{4}{5}$

If half-life of a substance is 3.8 days and its quantity is 10.38 gm. Then substance quantity remaining left after 19 days will be

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0.151 gm
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0.32 gm
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1.51 gm
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0.16 gm

Which is the correct expression for half-life

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$t_{1 / 2} = \log 2$
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$t_{1 / 2} = \frac{λ}{\log 2}$
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$t_{1 / 2} = \frac{λ}{\log 2} (2.303)$
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$t_{1 / 2} = \frac{2.303 \log 2}{λ}$

A nucleus ${}_{Z}^{A}A$ emits an $α$ -particle. The resultant nucleus emits a $β^{+}$ particle. The respective atomic and mass no. of the final nucleus will be

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Z – 3, A – 4
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Z – 1, A – 4
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Z – 2, A – 4
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Z, A – 2

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

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0.8 curie
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0.4 curie
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0.1 curie
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0.16 curie

In a mean life of a radioactive sample

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About 1/3 of substance disintegrates
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About 2/3 of the substance disintegrates
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About 90% of the substance disintegrates
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Almost all the substance disintegrates

Three fourth of the active decays in a radioactive sample in 3/4 sec. The half life of the sample is

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$\frac{1}{2}$ sec
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1 sec
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$\frac{3}{8}$ sec
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$\frac{3}{4}$ sec

During mean life of a radioactive element, the fraction that disintegrates is:

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e
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$\frac{1}{e}$
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$\frac{e - 1}{e}$
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$\frac{e}{e - 1}$

1 Curie is equal to

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$3 \times 10^{10}$ disintegrations/sec
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$3.7 \times 10^{7}$ disintegrations/sec
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$5 \times 10^{7}$ disintegrations/sec
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$3.7 \times 10^{10}$ disintegrations/sec

The electron emitted in beta radiation originates from

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Inner orbits of atoms
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Free electrons existing in nuclei
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Decay of a neutron in a nucleus
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Photon escaping from the nucleus

When a radioactive substance emits an $α$ -particle, its position in the periodic table is lowered by

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One place
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Two places
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Three places
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Four places

A radioactive nucleus emits a beta particle. The parent and daughter nuclei are

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Isotopes
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Isotones
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Isomers
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Isobars

If a radioactive substance reduces to $\frac{1}{16}$ of its original mass in 40 days, what is its half-life

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10 days
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20 days
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40 days
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None of these

A radioactive nucleus with Z protons and N neutrons emits an $α$ -particle, 2 $β$ -particles and 2 gamma rays. The number of protons and neutrons in the nucleus left after the decay respectively, are

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Z – 3, N – 1
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Z – 2, N – 2
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Z – 1, N – 3
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Z, N – 4

99% of a radioactive element will decay between

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6 and 7 half lives
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7 and 8 half lives
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8 and 9 half lives
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9 half lives

The half-life of a radioactive substance against $α$ -decay is $1.2 \times 10^{7}$ s. What is the decay rate for $4 \times 10^{15}$ atoms of the substance

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$4.6 \times 10^{12} atoms / s$
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$2.3 \times 10^{11} atoms / s$
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$4.6 \times 10^{10} atoms / s$
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$2.3 \times 10^{8} atoms / s$

In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life

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69.3%
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63%
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50%
0%

37%

The S.I. unit of radioactivity is

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Roentgen
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Rutherford
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Curie
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Becqueral

A radioactive material has an initial amount 16 gm. After 120 days it reduces to 1 gm, then the half-life of radioactive material is

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60 days
0%

30 days
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40 days
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240 days

The activity of a sample of a radioactive material is $A_{1}$ , at time $t_{1}$ and $A_{2}$ at time $t_{2}$ ( $t_{2}$ > $t_{1}$ ). If its mean life T, then

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$A_{1} t_{1} = A_{2} t_{2}$
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$A_{1} - A_{2} = t_{2} - t_{1}$
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$A_{2} = A_{1} e^{(t_{1} - t_{2}) / T}$
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$A_{2} = A_{1} e^{(t_{1} / t_{2}) T}$

Nucleus produced due to $α$ -decay of the nucleus ${}_{Z}^{A}X$ is

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${}_{Z + 2}^{A + 4}Y$
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${}_{Z}^{A}Y$
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${}_{Z - 2}^{A - 4}Y$
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${}_{Z - 4}^{A - 2}Y$

Which of the following processes represents a gamma-decay

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${}_{Z}^{A}X + γ \to {}_{Z - 1}^{A}X + a + b$
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${}_{Z}^{A}X + {}_{0}^{1}n \to {}_{Z - 2}^{A - 3}X + c$
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${}_{Z}^{A}X \to {}_{Z}^{A}X + f$
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${}_{Z}^{A}X + e^{- 1} \to {}_{Z - 1}^{A}X + g$

The half-life of ${}_{215}{At}$ is 100 $μs$ . The time taken for the radioactivity of a sample of ${}_{215}{At}$ to decay to 1/16th of its initial value is

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400 $μs$
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6.3 $μs$
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40 $μs$
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300 $μs$

The half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its $\frac{1}{16}$ th part

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12 h
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16 h
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48 h
0%

192 h

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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