Related InterviewSolutions

• Which of the following "is"//"are" correct?a)`alpha`-rays are more penetrating then `beta`-rays.b)`alpha`-rays have greater ionizing power than `beta`-rays.c)`beta`-particles are not present in the elements, yet they are emitted from the nucleus.d)`alpha`-rays are not emitted simultaneously with `alpha`- and `beta`-rays.A. `alpha` rays are more penetrating then `beta`-raysB. `alpha`-rays have greater ionizing power then `beta`-raysC. `beta`particle are not present in the nucleus, yet they are emitted from the nucleus.D. `gamma`-rays are not emitted simultaneously with `alpha` and `beta`-rays
• A radioactive substance is being consumed at a constant of `1 s^(-1)`. After what time will the number of radioactive nuclei becoem `100`. Initially, there were 200 nuceli present.A. 1 secB. 2 secC. In (2) secD. `(1)/(In (2)) sec`
• A radiaocatice isotope is being produced at a constant rate `X`. Half-life of the radioactive substance is `Y`. After some time, the number of radioactive nuceli become constant. The value of this constant is .
• Moderator is a material which is used to slow down the neutrons produced during nuclear fission. The neutrons from the source are of high speed and energy. Heavy water or graphite moderators slow down the speed of the neutrons. The energy of fast moving neutrons decreases from 2MeV to 0.02535 eV, it corresponds to the velocity of 220 m `"sec"^(-1)`. At this velocity, the neutrons are in thermal equilibrium with the moderator. such neutrons are called thermal neutrons. Thermal neutrons cause further fission reaction. The essential characterstices of moderators are: (i) Its molar mass must be low, (ii) It should not absorb neutrons. (iii) It should undergo elastic collisions with neutrons. A good moderator should:A. not be a gas onlyB. not have appertite for neutrons onlyC. be light in mass number onlyD. be all the above three
• Cyclotron is used to accelerateA. protonsB. deutronsC. neutronsD. electrons
• On large scale, tritium is produced by which of the following nuclear reaction?A. `._(3)^(6)Li + ._(0)^(1)n to ._(2)^(4)He + ._(1)^(3)T`B. `._(1)^(2)D + ._(1)^(2)D to ._(1)^(3)T + ._(1)^(1)H`C. `._(7)^(14)N + ._(0)^(1)n to ._(6)^(12)C + ._(1)^(1)T`D. `._(7)^(14)N + ._(1)^(1)H to ._(1)^(3)T` + other fragments
• The number of `alpha`-and `beta`-particles emitted in the nuclear reaction, `._(90)Th^(228) to ._(83)Bi^(212)`, respectively areA. `4 alpha` and `1 beta`B. `3 alpha` and `7 beta`C. `8 alpha` and `1 beta`D. `4 alpha` and `7 beta`
• Identify the nuclear reaction that differs from the rest:A. Positron emissionB. K-captureC. `beta`-decayD. `alpha`-decay
• The number of `alpha`-particles emitted per second by 1g fo `.^(226)Ra` is `.7 xx 10^(10)`. The decay constant is:A. `1.39 xx 10^(-11) sec^(-1)`B. `13.9 xx 10^(-11) sec^(-1)`C. `139 xx 10^(-10) sec^(-1)`D. `13.9 xx 10^(-10) sec^(-1)`
• Two elements `P` and `Q` have half-line of `10` and `15` minutes repectively. Freshly preapared sample of mixuture containing equal number of atoms is allowed to decay for `30` minutes. The ratio of number of atoms of `P` and `Q` in left in mixture is:A. 0.5B. 2C. 1D. 3