Problem 135
Match the lists I and II and pick the correct matching from the codes given below, Column-I (a) Isotope (b) Isobar (c) Isotone (d) Isosters (e) Isodiaphers Column-II (p) \({ }_{88} \mathrm{Ra}^{228}\) and \({ }_{89} \mathrm{Ac}^{228}\) (q) \({ }_{18} \mathrm{Ar}^{39}\) and \({ }_{19} \mathrm{~K}^{40}\) (r) \({ }_{1} \mathrm{H}^{2}\) and \({ }_{1} \mathrm{H}^{3}\) (s) \({ }_{92} \mathrm{U}^{235}\) and \({ }_{90}^{\mathrm{Th} 231}\) (t) \(\mathrm{CO}_{2}\) and \(\mathrm{N}_{2} \mathrm{O}\)
Problem 136
A fresh radioactive mixture containing short lived species \(X\) and \(Y\). Both the species together emitting \(8000 \alpha\) - particles per minute initially. 20 minutes later \(X\) was emitting \(\alpha\) - particles at the rate of 4500 per minute. If the half lives of the species \(\mathrm{X}\) and \(\mathrm{Y}\) are 10 minute and 500 hours, then what is the ratio of initial activities of \(\mathrm{X}\) and \(\mathrm{Y}\) in the mixture?
Problem 137
The disintegration rate of a certain radioactive sample at any instant is 5400 dpm. After 5 min the rate becomes \(2700 \mathrm{dpm}\). The half life of the sample in min is approximately
Problem 138
Half-life of a substance A, following first order kinetics is 5 days. Starting with \(100 \mathrm{~g}\) of \(\mathrm{A}\), amount left after 15 days is (a) \(25 \mathrm{~g}\) (b) \(50 \mathrm{~g}\) (c) \(12.5 \mathrm{~g}\) (d) \(6.25 \mathrm{~g}\)
Problem 139
\(\beta\) particle is emitted in a radioactive reaction when (a) a proton changes to neutron (b) a neutron changes to proton (c) a neutron changes to electron (d) an electron changes to neutron
Problem 140
The radio nucliede \({ }_{90} \mathrm{Th}^{234}\) undergoes two successive \(\beta\) decays followed by one \(\alpha\) decay. The atomic number and the mass number respectively of the resulting radio nucliede will be (a) 92 and 234 (b) 94 and 230 (c) 90 and 230 (d) 92 and 230
Problem 141
The half-life of a radioactive isotope is three hours. If the initial mass of the isotope were \(256 \mathrm{~g}\), the mass of it remaining undecayed after 18 hours would be (a) \(4.0 \mathrm{~g}\) (b) \(8.0 \mathrm{~g}\) (c) \(12.0 \mathrm{~g}\) (d) \(16.0 \mathrm{~g}\)
Problem 142
Consider the following nuclear reactions \({ }_{92} \mathrm{M}^{238} \longrightarrow \mathrm{y}^{\mathrm{x}}+2{ }_{2} \mathrm{He}^{4}\) \({ }_{\mathrm{y}} \mathrm{N}^{\mathrm{x}} \longrightarrow{ }_{\mathrm{B}} \mathrm{L}^{\mathrm{A}}+2 \beta^{+}\) The number of neutrons in element \(L\) is (a) 146 (b) 144 (c) 142 (d) 140
Problem 143
The half-life of a radio isotope is four hours. If the initial mass of the isotope was \(200 \mathrm{~g}\) the mass remaining undecayed after 24 hours is (a) \(2.084 \mathrm{~g}\) (b) \(3.125 \mathrm{~g}\) (c) \(4.167 \mathrm{~g}\) (d) \(1.042 \mathrm{~g}\)
Problem 144
A photon of hard \(\gamma\) radiation knocks a proton out of \({ }_{12} \mathrm{Mg}^{44}\) nucleus to form (a) the isotope of parent nucleus (b) the isobar of parent nucleus (c) the nuclide of \({ }_{11} \mathrm{Na}^{23}\) (d) the isobar of \(_{11} \mathrm{Na}^{23}\)
