MCQ 2011 Mark
The process of radioactive radiations remains unaffected due to:
- APhysical changes.
- BChemical changes.
- CElectric or magnetic fields.
- ✓All of the above.
Answer
View full question & answer→Correct option: D.
All of the above.
Questions · Page 5 of 5
M.C.Q (1 Marks)
MCQ 2021 Mark
Fusion reaction is also known as $......$
- AChemical reaction
- BElastic reaction
- ✓Thermonuclear reaction
- DPhotonuclear reaction
Answer
View full question & answer→Correct option: C.
Thermonuclear reaction
In nuclear physics,nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at very high speed and join to form a new type of atomic nucleus. During this process matter is not conserved because some of the matter of fusing nuclei is converted to photons also known as thermonuclear reaction.
MCQ 2031 Mark
Which one of the following has the identical property for isotopes?
- APhysical property.
- ✓Chemical property.
- CNuclear property.
- DThermal property.
Answer
View full question & answer→Correct option: B.
Chemical property.
MCQ 2041 Mark
A radioactive material undergoes decay by ejecting electrons. The electron ejected in this process is:
- ✓The electron from the decay of a neutron.
- BThe electron present in the nucleus.
- CThe resulting from the conversion of $\gamma\ \text{photon}.$
- DAn orbital electron.
Answer
View full question & answer→Correct option: A.
The electron from the decay of a neutron.
MCQ 2051 Mark
Mass number is denoted by:
- A$D$
- B$S$
- ✓$A$
- D$Z$
Answer
View full question & answer→Correct option: C.
$A$
The mass number $(A)$ is the number of nucleons, which is the total number of protons and neutrons in the nucleus of an atom.
MCQ 2061 Mark
In beta decay, the typical $Q$ value is approximately:
- A$2\ MeV$
- ✓$1\ MeV$
- C$1\ eV$
- D$10\ MeV$
Answer
View full question & answer→Correct option: B.
$1\ MeV$
The $Q$ value for a reaction is the amount of energy released by that reaction.
In beta decay, a typical $Q$ is around $1\ MeV.$
MCQ 2071 Mark
Chadwick was awarded the $1935$ nobel prize in physics for his discovery of the:
- AElectron.
- BProton.
- ✓Neutron.
- DPositron.
Answer
View full question & answer→Correct option: C.
Neutron.
MCQ 2081 Mark
Three specimens $\text{A, B, C}$ of same radioactive element has activities $1$ microcurie, $1$ rutherford and $1$ becquerel respectively. Which specimen has maximum mass?
- A$A$
- ✓$B$
- C$C$
- DAll have equal masses.
Answer
View full question & answer→Correct option: B.
$B$
MCQ 2091 Mark
The variation of decay rate of two radioactive samples A and B with time is shown in Fig. Which of the following statements are true?
- ADecay constant of A is greater than that of B, hence A always decays faster than B.
- BDecay constant of B is smaller than that of A but still its decay rate becomes equal to that of A at a later instant.
- CDecay constant of A is greater than that of B but it does not always decay faster than B.
- ✓B and C both
Answer
View full question & answer→Correct option: D.
B and C both
Solution:
It can be observed from the figure that the slope of curve A is greater that thet of curve B, it means the rate of decay is faster for A than that of B.
According to Rutherford and Soddy law for radioactive decay $-\Big(\frac{\text{dN}}{\text{dt}}\Big)\propto\lambda$, where decay,
Hence at point P, rate of decay for both A and B is the same.
It can be observed from the figure that the slope of curve A is greater that thet of curve B, it means the rate of decay is faster for A than that of B.
According to Rutherford and Soddy law for radioactive decay $-\Big(\frac{\text{dN}}{\text{dt}}\Big)\propto\lambda$, where decay,
Hence at point P, rate of decay for both A and B is the same.
MCQ 2101 Mark
Binding energy per nucleon for $\mathrm{C}^{12}$ is $7.68\ MeV$ and for $\mathrm{C}^{13}$ is $7.74\ MeV.$ The energy required to remove a neutron from $\mathrm{C}^{13}$ is:
- A$5.49\ MeV$
- ✓$8.46\ MeV$
- C$9.45\ MeV$
- D$15.49\ MeV$
Answer
View full question & answer→Correct option: B.
$8.46\ MeV$
$\mathrm{C}^{13}+$ energy $\rightarrow \mathrm{C}^{12}+\mathrm{n}$
Energy required to remove one neutron $=$ Difference in total binding energy
$= 13 \times 7.74 − 12 \times 7.68\ MeV$
$= 8.46\ MeV$
MCQ 2111 Mark
During a nuclear fission reaction:
- AA heavy nucleus breaks into two fragments by itself a light nucleus bombarded by thermal neutrons breaks up.
- BA light nucleus bombarded by thermal neutrons breaks up.
- ✓A heavy nucleus bombarded by thermal neutrons breaks up.
- DTwo light nuclei combine to give a heavier nucleus and possible other products.
Answer
View full question & answer→Correct option: C.
A heavy nucleus bombarded by thermal neutrons breaks up.
In a nuclear reactor, a large fissile atomic nucleus like uranium$-235$ absorbs a thermal neutron and undergoes a nuclear fission reaction. The heavy nucleus splits into two or more lighter nuclei releasing gamma radiation and free neutrons.
MCQ 2121 Mark
Atomic number $(Z)$ of a neutral atom and mass number $(A)$ of an atom are equal to:$($Here $n =$ number of neutrons and $p =$ number of protons$):$
- A$Z = n$ and $A = n+p$
- B$Z = e$ and $A = n+e$
- ✓$Z = p$ and $A = n+p$
- D$Z = n$ and $A = p+e$
Answer
View full question & answer→Correct option: C.
$Z = p$ and $A = n+p$
The atomic number $= Z =$ no. of protons $= p$
The mass no. $= A =$ no. of protons $(p) +$ no. of neutrons$(n) = n + p$
MCQ 2131 Mark
If a star can convert all the He nuclei completely into oxygen nuclei. The energy released per oxygen nuclei is $[$Mass of He nucleus is $4.0026$ amu and mass of Oxygen nucleus is $15.9994$ amu$]:$
- A$7.6\ MeV.$
- B$56.12\ MeV.$
- ✓$10.24\ MeV.$
- D$23.9\ MeV.$
Answer
View full question & answer→Correct option: C.
$10.24\ MeV.$
MCQ 2141 Mark
The rest energy involved in a mass of one atomic mass unit is $...... \ eV.$
- ✓$931\ MeV$
- B$1.6\ eV$
- C$9.3\ MeV$
- D$9.1$
Answer
View full question & answer→Correct option: A.
$931\ MeV$
The mass of $1$ amu is equivalent to an energy of $931\ MeV.$
MCQ 2151 Mark
The order of magnitude of radius of nucleus is $......$
- ✓$ 10^{-15} \mathrm{~m} $
- B$ 10^{15} \mathrm{~m} $
- C$ 10^{-10} \mathrm{~m} $
- D$ 10^{10} \mathrm{~m} $
Answer
View full question & answer→Correct option: A.
$ 10^{-15} \mathrm{~m} $
The order of magnitude of nuclear radii is $1$ fermi $= 10^{-15}$ meters.
MCQ 2161 Mark
Deuterium is the most common isotope of hydrogen. How many neutrons does it have?
- A$4$
- B$3$
- C$1$
- ✓$0$
Answer
View full question & answer→Correct option: D.
$0$
Deuterium: $\frac{2}{1}H$
Mass number: $A = 2$
Atomic number $($or number of protons$), Z = 1$
Number of neutrons, $Nn = A − Z = 2 − 1 = 1$
Mass number: $A = 2$
Atomic number $($or number of protons$), Z = 1$
Number of neutrons, $Nn = A − Z = 2 − 1 = 1$
MCQ 2171 Mark
Which of the following is a wrong description of binding energy of a nucleus?
- AIt is the energy required to break a nucleus into its constituent nucleons.
- BIt is the energy made available when free nucleons combine to form a nucleus.
- CIt is the sum of the rest mass energies of its nucleons minus the rest mass energy of the nucleus.
- ✓It is the sum of the kinetic energy of all the nucleons in the nucleus.
Answer
View full question & answer→Correct option: D.
It is the sum of the kinetic energy of all the nucleons in the nucleus.
Binding energy of a nucleus is defined as the energy required to break the nucleus into its constituents. It is also measured as the $Q-$value of the breaking of nucleus, i.e. the difference between the rest energies of reactants $($nucleus$)$ and the products $($nucleons$)$ or the difference between the kinetic energies of the products and the reactants.
MCQ 2181 Mark
The mass defect per nucleon is called:
- ABinding energy
- ✓Packing fraction
- CIonisation energy
- DExcitation energy
Answer
View full question & answer→Correct option: B.
Packing fraction
Nuclear binding energy can be computed from the difference in mass of a nucleus, and the sum of the masses of the number of free neutrons and protons that make up the nucleus. Once this mass difference, called the mass defect or mass deficiency, is known, Einstein's mass$-$energy equivalence formula can be used to compute the binding energy of any nucleus.
Early nuclear physicists used to refer to computing this value as a "packing fraction" calculation.
MCQ 2191 Mark
During a negative beta decay:
- AAn atomic electron is ejected.
- BAn electron which is already present within the nucleus is ejected.
- ✓A neutron in the nucleus decays emitting an electron.
- DA proton in the nucleus decays emitting an electron.
Answer
View full question & answer→Correct option: C.
A neutron in the nucleus decays emitting an electron.
Negative beta decay is given as
$\text{n}\rightarrow\text{p + e}^-+\bar{\text{v}}$
Neutron decays to produce proton, electron and anti$-$neutrino.
MCQ 2201 Mark
Mass of atom expressed in atomic mass unit is:
- ✓Atomic mass
- BMolecular mass
- CAtomic number
- DNone of the above
Answer
View full question & answer→Correct option: A.
Atomic mass
The mass of an atom expressed in amu is known as atomic mass. atomic mass unit defined as a unit of mass used to express atomic and molecular weights, equal to one$-$twelfth of the mass of an atom of carbon$-12.$
MCQ 2211 Mark
$\gamma - \text{rays}$ are deflected by:
- AAn electric field but not by a magnetic field.
- BA magnetic field but not by an electric field.
- CBoth electric and magnetic field.
- ✓Neither by electric field nor by magnetic field.
Answer
View full question & answer→Correct option: D.
Neither by electric field nor by magnetic field.
MCQ 2221 Mark
Substances which have identical chemical properties but differ in atomic weight are called.
- AIsothermals
- ✓Isotopes
- CIsotropics
- DElementary particles
Answer
View full question & answer→Correct option: B.
Isotopes
Isotopes are atoms of the same element having the same numbers of protons, but different numbers of neutrons. They have same chemical properties due to the same electronic configuration but different physical properties.
MCQ 2231 Mark
A nuclear reaction with positive $Q$ value is:
- AEndothermic
- ✓Exothermic
- CEither endothermic or exothermic
- DNeither endothermic nor exothermic
Answer
View full question & answer→Correct option: B.
Exothermic
An exothermic reaction is that in which heat is released.
An exothermic reaction is that in which heat is absorbed.
In a nuclear reaction, if the mass of the product nucleus and outgoing particle is less than the mass of the target nucleus and bombarding particle, then energy is released $($exothermic reaction$),$ and $Q-$value is $+ve.$
MCQ 2241 Mark
Which of the following isotopes is likely to be most stable?
- A$71\text{Zn}\\30$
- B$66\text{Zn}\\30$
- ✓$40\text{Ca}\\20$
- DNone of these
Answer
View full question & answer→Correct option: C.
$40\text{Ca}\\20$
The nucleus of each atom contains protons and neutrons. While the number of proton defines the element and the number of neutrons defines the isotope of the element. Radioactive isotopes are unstable and decays into other elements.
MCQ 2251 Mark
For nuclei with A > 100:
- AThe binding energy of the nucleus decreases on an average as A increases.
- BThe binding energy per nucleon decreases on an average as A increases.
- CIf the nucleus breaks into two roughly equal parts, energy is released.
- ✓B and C both
Answer
View full question & answer→Correct option: D.
B and C both
Explanation:
Binding energy per nucleon varies in a way that it depends on the actual value of mass number (A). As the mass number (A) increases, the binding energy also increases and reaches its maximum value of 8.7MeV for A(50-80) and for A > 100. The binding energy per nucleon decreases as A increases and the nucleus breaks into two or more atoms of roughly equal parts so as to attain stability and binding energy of mass number between 50-80.
Binding energy per nucleon varies in a way that it depends on the actual value of mass number (A). As the mass number (A) increases, the binding energy also increases and reaches its maximum value of 8.7MeV for A(50-80) and for A > 100. The binding energy per nucleon decreases as A increases and the nucleus breaks into two or more atoms of roughly equal parts so as to attain stability and binding energy of mass number between 50-80.