NEET Practice Questions (MCQs) with Answers & Solutions

(c) Neutrino is a charge less, spin particle.

(a) Number of fissions per second = $\frac{\mathrm{Power} \mathrm{output}}{\mathrm{Energy} \mathrm{released} \mathrm{per} \mathrm{fission}}=\frac{3.2\times {10}^6}{200\times {10}^6\times 1.6\times {10}^{-19}}=1\times {10}^{17}$

$\Rightarrow$ Number of fission per minute = $60\times {10}^{17}=6\times {10}^{18}$

(c)

(a) $\mathrm{X}\left(\mathrm{n}, \mathrm{\alpha }\right){ }_3{\mathrm{Li}}^7\Rightarrow {}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}+{}_0{}^1\mathrm{n}\to {}_3{}^7\mathrm{Li}+{}_2{}^4\mathrm{He}$

Z = 3+2 = 5 and A = 7+4-1 = 10

$\therefore {}_5{}^{10}\mathrm{X}={}_5{}^{10}\mathrm{B}$

(a) The energy is released due to bombarding of neutrons on ${}_{92}U^{235}$

(b) Mass of electron = mass of positron = $9.1\times {10}^{-31}$kg
Energy released $\mathrm{E}=\left(2\mathrm{m}\right){\mathrm{c}}^2$
= $2\times 9.1\times {10}^{-31}\times (3\times {10}^8{)}^2=1.6\times {10}^{-13 }\mathrm{J}$

(c) Mass of a uranium nucleus $=92\times 1.6725\times {10}^{-27}+143\times 1.6747\times {10}^{-27}=393.35\times {10}^{-27} \mathrm{kg}$

Number of nuclei in the given mass $=\frac{1}{393.35\times {10}^{-27}}=2.542\times {10}^{24}$

Energy released $=200\times 2.542\times {10}^{24} \mathrm{MeV}$

$=5.08\times {10}^{26} \mathrm{MeV}=8.135\times {10}^{13}\mathrm{J}=8.2\times {10}^{13}\mathrm{J}$

(a) Total mass of reactants $=\left(2.0141\right)\times 2=4.0282 \mathrm{amu}$
Total mass of products =4.0024 amu
Mass defect = 4.0282 amu-4.0024 amu = 0.0258 amu

$\therefore$ Energy released E = 931$\times$0.0258 = 24 MeV

(b) ${}_7{}^{14}\mathrm{N}+{}_2{}^4\mathrm{He}\to {}_8{}^{17}\mathrm{O}+{}_1{}^1\mathrm{H}$

(b) Fusion process results in increase in mass number. For light nuclei, fusion process increases the binding energy per nucleon which increases stability. So light nuclei are suitable for fusion process.