19) A certain radio active substance has a half life of 30 days. What is thedisintegrationconstant? Find its average life.20) Find the time required to decay 3/4th of a radioactive sample whose half life is60 days.21) Neon -23 decays in the following way23Ne10 --------------- 23Na11 + 0e-1 +γFind the minimum and maximum kinetic energy that the β-particle can have.The atomic masses of 23Ne10 and 23Na11 are 22.99454 and 22.98984respectively.22) The disintegration rate of a certain radioactive sample at any instant is 4750disintegrations per minute. Five minutes later the rate becomes 2700 perminute. Calculatea) Decay constantb) Half-life of the sample23) Explain with an example, whether neutron-proton ratio increases ordecreases during beta decay.24) The half life period of radioactive element A is the same as the mean half timeof another radioactive element B.Initially both of them have the same number ofatoms. The radioactive element B decays faster than A. Explain why?25) Obtain the binding energy of a nitrogen nucleus from the following datamh=1.007834; mn=1.00867; mN=14.03074Give your answer in MeV.26) Write nuclear equations fora) The α-decay of 226Ra88b) The β- -decay of 32P15c) The β+ decay of32P1527) A neutron is absorbed by a 6Li3 nucleus with the subsequent emission of analpha particle.

i) Write the corresponding nuclear reactions.ii) Calculate the energy released in MeV, in this reaction.
Extra Questions
1. Calculate the energy released in the following nuclear reaction.
2. When a deutron of mass 2.0141amu is absorbed by a 3 Li 6 nucleus ofmass 6.015amu, the nucleus splits into two -particles each of mass4.0026amu. Calculate energy carried by each -particles.3. A nucleus 10 Na 23 undergoes -decay to give 11 Na 23. Write down thenuclear reaction. Calculate KE of electron. Given mass of 10 Na 23 =
4. A neutron is absorbed by 3 Li 6 nucleus with the subsequent emission of a-particle. (i) Write the corresponding nuclear reaction.(ii) Calculate the energy released. M 3Li6 = 6.015126amu, m(n) =
5. The mass of the star is 5 * 1032 kg. It generates energy at the rate of 5 *1030 W. How long does it take to convert all Helium to carbon at this rate.
6. Prove mathematically that the fraction N / N0 of a radioactive element leftover after a time ‘t’ equals 1 / x where x = 2 t/T. T is half-life period.