Chapter 21

What is A in the following reaction? \({ }_{12} \mathrm{Mg}^{26}+{ }_{1} \mathrm{H}^{2} \longrightarrow{ }_{12} \mathrm{Mg}^{27}+\mathrm{A}\) (a) \({ }_{1} \mathrm{H}^{1}\) (b) \({ }_{0} \mathrm{n}^{1}\) (c) \(\mathrm{D}^{2}\) (d) \(\gamma\) rays

Which of the following is easily stopped by air? (a) uv rays (b) X-rays (c) \(\alpha\) rays (d) \(\gamma\) rays

\({ }_{90}^{232} \mathrm{Th} \longrightarrow{ }_{82}^{208} \mathrm{~Pb}\) The number of \(\alpha\) and \(\beta\) particle emitted during the above reaction is (a) \(8 \alpha\) and \(4 \beta\) (b) \(8 \alpha\) and \(16 \beta\) (c) \(4 \alpha\) and \(2 \beta\) (d) \(6 \alpha\) and \(4 \beta\)

Which one of the following statement is correct? (a) the end nuclide formed in thorium (4n) series is \({ }_{83} \mathrm{Bi}^{-200}\). (b) \(_{7} \mathrm{~N}^{15}\) and \({ }_{\mathrm{s}} \mathrm{O}^{16}\) are isobars (c) \({ }_{20} \mathrm{Ca}^{40}\) has magic number of protons and magic number of neutrons (d) The radius (R) of a nuclide of mass number \(\mathrm{A}\) is given by the equation \(\mathrm{R}=\mathrm{R}_{0}(\mathrm{~A})^{1 / 2}\left(\mathrm{R}_{0}=\right.\) constant \()\)

Which one of the following radioisotopes is used in the treatment of blood cancer? (a) \(\mathrm{Co}^{62}\) (b) \(\mathrm{P}^{32}\) (c) \(\mathrm{Na}^{24}\) (d) \(I^{131}\)

Unstable substances exhibit higher radioactivity due to (a) high \(\mathrm{p} / \mathrm{n}\) ratio (b) low \(\mathrm{p} / \mathrm{n}\) ratio (c) \(\mathrm{p} / \mathrm{n}=1\) (d) both (a) and (b)

Atom bomb is based on the principle of (a) nuclear fusion (b) nuclear fission (c) nuclear transformation (d) carbon dating

The moderator used in nuclear reactors is (a) TEL (b) \(\mathrm{D}_{2} \mathrm{O}\) (c) \(\mathrm{H}_{2} \mathrm{O}_{2}\) (d) \(\mathrm{R}-\mathrm{O}-\mathrm{R}\)

The element used for carrying out the nuclear reaction is (a) Thorium- 232 (b) Uranium-238 (c) Plutonium-239 (d) Neptunium- 293

If the mass defect of a nuclide is \(3.32 \times 10^{-26} \mathrm{~g}\), its binding energy is ..... MeV (a) \(27.93\) (b) \(9.31\) (c) \(37.24\) (d) \(18.62\)

Fusion bomb involves (a) explosion of TNT (b) combustion of oxygen (c) destruction of heavy nucleus into smaller nuclei (d) combination of lighter nuclei into bigger nucleus

If the mass defect of \(\mathrm{X}^{9}\) is \(0.090 \mathrm{amu}\), then the binding energy per nucleon is (1 amu = \(921.5 \mathrm{MeV}\) ) (a) \(83.0 \mathrm{MeV}\) (b) \(9.315 \mathrm{MeV}\) (c) \(8.38 \mathrm{MeV}\) (d) \(931.5 \mathrm{MeV}\)

\({ }_{27} \mathrm{Co}^{60}\) is radioactive because (a) it has high \(\mathrm{n} / \mathrm{p}\) ratio (b) it has high \(\mathrm{p} / \mathrm{n}\) ratio (c) its atomic number is high (d) none of these

A heavy element has atomic number \(\mathrm{X}\) and mass number Y. Correct relation between \(\mathrm{X}\) and \(\mathrm{Y}\) is (a) \(\mathrm{X}=\mathrm{Y}\) (b) \(\mathrm{X}>\mathrm{Y}\) (c) \(\mathrm{X}<\mathrm{Y}\) (d) \(\mathrm{X}=Z(1-\mathrm{Y})\)

Decay of \(_{92} \mathrm{U}^{235}\) is \(\ldots \ldots\) order reaction (a) first (b) second (c) third (d) zero

Order of radioactive disintegration reaction is (a) third (b) second (c) first (d) zero

In which radiation, mass number and atomic number will not change? (a) \(\alpha\) (b) \(\beta\) (c) \(\alpha\) and \(2 \beta\) (d) \(\gamma\)

The half lives of two radioactive nuclides \(\mathrm{A}\) and \(\mathrm{B}\) are 1 and 2 min respectively. Equal weights of \(A\) and \(B\) are taken separately and allowed to disintegrate for \(4 \mathrm{~min}\). What will be the ratio of weights of \(\mathrm{A}\) and \(\mathrm{B}\) disintegrated? (a) \(1: 2\) (b) \(1: 1\) (c) \(1: 3\) (d) \(5: 4\)

In the nuclear fusion \({ }_{1} \mathrm{H}^{2}+{ }_{1} \mathrm{H}^{2} \longrightarrow{ }_{2} \mathrm{He}^{4}\), the masses of \({ }_{1} \mathrm{H}^{2}\) and \({ }_{2} \mathrm{H}^{4}\) are \(2.014 \mathrm{~m}_{\mathrm{a}}\) and \(4.003 \mathrm{~m}_{\mathrm{u}}\) respectively. The energy released per atom of helium formed is ........ MeV (a) \(4.31\) (b) \(13.26\) (c) \(16.76\) (d) \(23.275\)

In successive emission of \(\beta\) and \(\alpha\) particles, how many \(\alpha\) and \(\beta\) particles should be emitted for the natural \(\left(4 n+1\right.\) series) conversion of \({ }_{94} \mathrm{Pu}^{241}\) to \({ }_{92} \mathrm{U}^{233}\) ? (a) \(2 \alpha, \beta\) (b) \(2 \alpha, 2 \beta\) (c) \(2 \alpha, 3 \beta\) (d) \(\alpha, 2 \beta\)

What will be the binding energy of \(\mathrm{O}^{16}\), if the mass defect is \(0.210\) amu? (a) \(1.89 \times 10^{10} \mathrm{~J} \mathrm{~mol}^{-1}\) (b) \(1.89 \times 10^{12} \mathrm{~J} \mathrm{~mol}^{-1}\) (c) \(1.89 \times 10^{13} \mathrm{~J} \mathrm{~mol}^{-1}\) (d) \(1.89 \times 10^{14} \mathrm{~J} \mathrm{~mol}^{-1}\)

The compound used for the preparation of \(U F_{6}\) in the enrichment of \({ }_{92} \mathrm{U}^{235}\) is (a) HF (b) \(\mathrm{CaF}_{2}\) (c) \(\mathrm{ClF}_{3}\) (d) \(\mathrm{AlF}_{3}\)

When \({ }_{13} \mathrm{Al}^{27}\) is bombarded with \(\alpha\) particle, a radioactive isotope of phosphorus \({ }_{1 s} \mathrm{P}^{30}\) is formed. Which particle is emitted along with \({ }_{15} \mathrm{P}^{30}\) ? (a) deuteron (b) proton (c) electron (d) neutron

\({ }_{1} \mathrm{H}^{1}+{ }_{1} \mathrm{H}^{3} \longrightarrow{ }_{2} \mathrm{He}^{4}\) this represent (a) \(\beta\) decay (b) fusion (c) fission (d) none of these

The age of most ancient geological formations is estimated by (a) potassium-argon method (b) carbon- 14 dating method (c) radium-silicon method (d) uranium-lead method

In a radioactive decay, an emitted electron comes from (a) the nucleus of atom (b) the orbit with principal quantum number 1 (c) the inner orbital of the atom (d) the outermost orbit of the atom

The projectile used to bombard, \(\mathrm{N}^{14}\) to get \({ }_{8} \mathrm{O}^{17}\) and a proton is (a) \({ }_{2} \mathrm{He}^{4}\) (b) \({ }_{0} \mathrm{n}^{1}\) (c) \({ }_{1} \mathrm{H}^{1}\) (d) \({ }_{1} \mathrm{H}^{2}\)

The half-life of a radioactive isotope is \(1.5\) hours. The mass of it that remains undecayed after 6 hours is (the initial mass of the isotope is \(64 \mathrm{~g}\) ) (a) \(32 \mathrm{~g}\) (b) \(16 \mathrm{~g}\) (c) \(8 \mathrm{~g}\) (d) \(4 \mathrm{~g}\)

The binding energy of an element is \(64 \mathrm{MeV}\). If BE per nucleon is \(6.4\), the number of nucleons are (a) 10 (b) 64 (c) 16 (d) 6

The reaction \({ }_{5} \mathrm{~B}^{3} \longrightarrow{ }_{4} \mathrm{Be}^{8}+{ }_{1} \mathrm{e}^{0}\) takes place due to (a) \(\alpha\) decay (b) \(\beta\) decay (c) positron decay (d) electron capture

The common moderator of a nuclear reactor (a) \(\mathrm{D}_{2} \mathrm{O}\) (b) graphite (c) beryllium (d) all are correct

The half-life of a radioactive nuclide is 10 months. The fraction of the substance left behind after 40 months is (a) \(1 / 2\) (b) \(1 / 4\) (c) \(1 / 8\) (d) \(1 / 16\)

Carbon- 14 dating method is based on the fact that (a) C-14 fraction is same in all objects (b) C-14 is highly insoluble (c) ratio of carbon- 14 and carbon-12 is constant (d) all the above

When a radioactive element emits successively one \(\alpha\). particle and two \(\beta\) particles, the mass number of the daughter element (a) is reduced by 4 units (b) remains the same (c) is reduced by 2 units (d) is increased by 2 units

A nuclide of an alkaline earth metal undergoes radioactive decay by emission of the \(\alpha\) particle in succession. The group of the periodic table to which the resulting daughter element would belong is (a) Gp 14 (b) Gp 6 (c) Gp 16 (d) Gp 4

The number of \(\alpha\) and \(\beta\) particle emitted in the nuclear reaction \({ }^{228} \mathrm{Th}_{90} \longrightarrow{ }^{212} \mathrm{Bi}_{\mathrm{g} 3}\) are (a) \(4 \alpha\) and \(1 \beta\) (b) \(3 \alpha\) and \(7 \beta\) (c) \(8 \alpha\) and \(1 \beta\) (d) \(4 \alpha\) and \(7 \beta\)

The compound used in enrichment of the uranium in nuclear power plant is (a) UF \(_{6}\) (b) \(\mathrm{U}_{3} \mathrm{O}_{8}\) (c) \(\mathrm{UCl}_{4}\) (d) \(\mathrm{UO}_{2}\left(\mathrm{NO}_{3}\right)_{2}\)

\({ }_{92} \mathrm{U}^{238}\) is radioactive and it emits \(\alpha\) and \(\beta\) particles to form \({ }_{82} \mathrm{~Pb}^{206} .\) The number of \(\alpha\) and \(\beta\) particles are respectively (a) 8,6 (b) 6,8 (c) 4,2 (d) 8,4

An element X loses one \(\alpha\) and two two \(\beta\) particles in three successive stages. The resulting elements will be (a) an isotope of \(\mathrm{X}\) (b) an isobar of \(X\) (c) an isotone of \(X\) (d) X itself

\({ }_{7} \mathrm{~N}^{13}\) changes to \({ }_{6} \mathrm{C}^{13}\) by emission of (a) electron (b) neutron (c) positron (d) proton

If uranium (mass number 238 and atomic number 92 ) emits an \(\alpha\) particle, the product has mass number and atomic number (a) 234 and 90 (b) 236 and 92 (c) 238 and 90 (d) 236 and 90

Which of the following notations shows the product incorrectly? (a) \({ }_{5} \mathrm{~B}^{10}(\alpha, \mathrm{n})_{7} \mathrm{~N}^{13}\) (b) \({ }_{96} \mathrm{Cm}^{242}(\alpha, 2 \mathrm{n}){ }_{97} \mathrm{BK}^{243}\) (c) \({ }_{7} \mathrm{~N}^{14}(\mathrm{n}, \mathrm{p})_{6} \mathrm{C}^{14}\) (d) none of these

Loss of a \(\beta\) particle is equivalent to (a) increase of one proton only (b) decrease of one neutron only (c) both (a) and (b) (d) none of these

Which of the following is a fusion reaction? (a) \({ }_{98} \mathrm{U}^{255}+{ }_{0} \mathrm{n}^{1} \longrightarrow{ }_{36} \mathrm{Ba}^{141}+{ }_{36} \mathrm{Kr}^{92}+3_{0} \mathrm{n}^{1}\) (b) \({ }_{92} \mathrm{Fe}^{259}+{ }_{0} \mathrm{n}^{1} \longrightarrow{ }_{92} \mathrm{U}^{239}+\mathrm{Y}\) (c) \({ }_{26} \mathrm{Fe}^{55}+{ }_{-1} \mathrm{e}^{0} \longrightarrow{ }_{25} \mathrm{Mn}^{55}\) (d) \({ }_{1} \mathrm{H}^{1}+{ }_{1} \mathrm{H}^{1}+2 \underset{0}{\mathrm{n}}^{1} \longrightarrow \mathrm{He}^{4}+\) energy

The binding energy of an element is \(64 \mathrm{meV}\). If \(\mathrm{BE} /\) Nucleon is \(6.4\), the number of nucleons are (a) 10 (b) 64 (c) 16 (d) \(6.4\)

Nuclear reactors are usually surrounded by lead and concrete. Which of the following is this safety precaution particularly for? (a) neutron (b) \(\alpha\) particle (c) \(\beta\) particle (d) \(\gamma\) rays

Two radioactive elements A and B have decay constant \(\lambda\) and \(10 \lambda\) respectively. If the decay begins with the same number of atoms of the \(\mathrm{n}\), the ratio of atoms of \(\mathrm{A}\) to those of B after time \(1 / 9 \lambda\) will be (a) \(\mathrm{e}^{-3}\) (b) \(\mathrm{e}^{2}\) (c) \(\mathrm{e}\) (d) \(\mathrm{e}^{-1}\)

During a \(\mathrm{K}\)-electron capture (a) X-rays are emitted (b) neutrous are emitted (c) \(\alpha\) particles are emitted (d) \(\gamma\) rays are emitted

\({ }_{7} \mathrm{~N}^{13}\) changes to \({ }_{6} \mathrm{C}^{13}\) by the emission of (a) proton (b) electron (c) neutron (d) positron

The half-life of a radioactive isotope is 3 hours. If the initial mass of the isotope was \(300 \mathrm{~g}\), the mass which remained undecayed in 18 hours would be (a) \(4.68 \mathrm{~g}\) (b) \(2.34 \mathrm{~g}\) (c) \(1.17 \mathrm{~g}\) (d) \(9.36 \mathrm{~g}\)