A fission reaction is given by , where x and y are two particles. Considering to be at rest, the kinetic energies of the products are denoted by (2MeV) and (2MeV), respectively. Let the binding energies per nucleon of , and be 7.5 MeV, 8.5 MeV and 8.5 MeV, respectively. Considering different conservation law, the correct option(s) is(are)
1. x = n, y = n, = 129 MeV, = 86 MeV
2. x = p, y = , = 129 MeV, = 86 MeV
3. x = p, y = n, = 129 MeV, = 86 MeV
4. x = n, y = n, = 86 MeV, = 129 MeV
The following fusion reaction takes place
If 2 kg of deuterium is subjected to above reaction, the energy released is used to light a 100 W lamp, how long will the lamp glow
1. 2 x 10 years
2. 3 x 10 years
3. 5 x 10 years
4. 7 x 10 years
A radioactive sample having the activity has twice the number of nuclie as another sample of activity . If = , then the ratio of half life of to the life of is
1. 4
2. 2
3. 0.25
4. 0.75
If T is the half life of a radioactive material, then the fraction that would remain after a time is
1.
2.
3.
4.
The half life of a radio active substance is 20 days. If part of the substance has decayed in time and part of it has decayed in time then the time interval between and is =
1. 5 days
2. 10 days
3. 20 days
4. 40 days
The number of atoms of a radioactive substance of half-life T is at t = 0. The time necessary to decay from atoms to atoms will be
1. T
2. T n5
3. Tn
4. T
Two samples X and Y contain equal amount of radioactive substances. If th of the sample X and th of the sample Y, remain after 8 hours, then the ratio of half periods of X and Y is
1. 2 : 1
2. 1 : 2
3. 1 : 4
4. 1 : 16
For a radioactive nucleus, the mean life is T. If the initial nuclei are n at t = 0, the number of decays between time 0 and t, is
1. nTe
2. n(1 - e)
3. nT(1 - e)
4. ne
During mean life of a radioactive element, the fraction that disintegrates is
1. e
2.
3.
4.
Two radioactive substances A and B decay constants 5 and respectively. At t = 0 they have the same number of nuclei. The ratio of numbers of nuclei of A to those of B will be after a time interval
1.
2.
3.
4.
The activity of a sample of a radioactive material is at time and at time . If its mean life is T, then
1.
2.
3.
4.
Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0, number of P species are 4 and that of Q are . Half-life of P (for conversion to R) is 1 minute where as that of Q is 2 minutes. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be
1.
2.
3.
4.
Mass spectrometric analysis of potassium and argon atoms in a Moon rock sample shows that the ratio of the number of (stable) atoms present to the number of (radioactive) atoms is 10.3. Assume that all the argon atoms were produced by the decay of potassium atoms, with a half-life of 1.25 x 10 yr. How old is the rock ?
1. 2.95 x 10 yr
2. 2.95 x 10 yr
3. 4.37 x 10 yr
4. 4.37 x 10 yr
A radioactove sample of decays to Pb through a process for which half life is 4.5 x 10 years. The ratio of number of nuclei of Pb to after a time of 1.5 x 10 years (given = 1.26)
1. 0.12
2. 0.26
3. 1.2
4. 0.37