The rest mass of an electron as well so that of positron is 0.51 cMeV. When an electron and positron are annihilate they produce gamma-rays of wavelength(s)
Calculate and compare the energy released by (a) Fusion of 1.0 kg of hydrogen deep within Sun (b) The fission of 1.0 kg of 235U in a fission reactor
The Q value of a nuclear reaction, A + b → C + d, is defined by
where, the masses refer to the respective nuclei. Determine from the given data the Q-value of the following reactions and state whether the reactions are exothermic or endothermic.
Atomic masses are given to be
The radio nuclide 11C decays according to
611C→511B+e++ν: T1/2 =20.3 min
The maximum energy of the emitted positron is 0.960 MeV.
Given the mass values:
m(611C)=11.011434u and m(611B)=11.009305u
Calculate Q and compare it with the maximum energy of the positron emitted.
The nucleus 1123Ne decays by β− emission. Write down the β - decay equation and determine the maximum kinetic energy of the electrons emitted. Given that:
A piece of wood from the ruins of an ancient building was found to have a C14 activity of 12 disintegration per minute per gram of its carbon content. The C14 activity of the living wood is 16 disintegration per minute per gram. How long ago did the tree, from which the wooden sample came, di? Given half-life of C14 is 5760 years.
In a periodic table the average atomic mass of magnesium is given as 24.312 u. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are 1224Mg (23.98504u), 1225Mg (24.98584u) and 1226Mg (25.98259u). The natural abundance of 1224Mg is 78.99% by mass. Calculate the abundances of other two isotopes.
The normal activity of living carbon-containing matter is found to be about 15 decays per minute for every gram of carbon. This activity arises from the small proportion of radioactive 614C present with the stable carbon isotope 612C. When the organism is dead, its interaction with the atmosphere (which maintains the above equilibrium activity) ceases and its activity begins to drop. From the known half-life ( 5730 years) of 614C, and the measured activity, the age of the specimen can be approximately estimated. This is the principle of 614C dating used in archaeology. Suppose a specimen from Mohenjodaro gives an activity of 9 decays per minute per gram of carbon. Estimate the approximate age of the Indus-Valley civilisation.