An Electron And Its Antiparticle Are Annihilated After Collision. How Much Energy Will Be Obtained? What Will Be The Wavelength Of The Emitted Radiation (energy)? (Mass Of Electron , Speed Of Light  and Planck’s Constant )

A radioactivity sample contains 2.2 mg of pure  which has half-life period of 1224 seconds. Calculate the number of atoms present initially.

A small quantity of solution containing  radionuclide (half-life 15 hours) of activity 1.0 microcurie is injected into the blood of a person. A sample of the blood of volume 1 cm³ taken after 5 hours show an activity of 296 disintegrations per minute. Determine the total volume of blood in the body of the person.

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The isotopes  occur in nature in the ratio 140 : 1. Assuming that at the time of earth’s formation they were present in equal ratio, make an estimation of the age of the earth. The half-lives of  respectively.

A radioactive isotope X has a half-life of 3 seconds. At t = 0 second, a given sample of this isotope X contains 8000 atoms. Calculate the number of decays per second in the sample at t = t₁ second.    

A radioactive element of atomic weight 99 has a half-life of 6 hours. Find the activity in a solution containing 1 gram of the element in the beginning. The Avogadro’s number is .   

In an ore containing uranium, the ratio of  nuclei is 3. Calculate the age of the ore, assuming that all the lead present in the ore is the final stable product of . Take the half-life of .

The mean lives of a radioactive substance are 1620 years and 405 years for-emission and -emission respectively. Find out the time during which three-fourth of a sample will decay if it is decaying both by -emission and-emission simultaneously.

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Calculate the energy in joule equivalent to the mass of one proton. The mass of proton is 1.00728 u. Express the energy in kilowatt-hour also.

An electron-positron pair is produced by the materialization of a gamma-ray photon of 2.26 MeV. How much kinetic energy is imparted to each of the charged particle? The rest mass of elector is  and the speed of light is . Take .

A 1-MeV positron collides head-on with a 1-MeV electron and they are annihilated, producing -rays. Compute total energy of the resulting -rays and their wavelength.Given : rest mass of electron or positron = 0.000549 u, .