Nuclei · Question 42

Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be

1. (3)1/3 : 1
2. 1 : 1
3. 1 : 3
4. 3 : 1

Two radioactive materials X1 and X2 have decay constants 5 and respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that of X2 will be 1e after a time

1. 14
2. e
4. 12

A nucleus AZX has mass represented by M(A, Z). If Mp and Mn denote the mass of proton and neutron respectively and B.E. the binding energy in MeV, then

1. B.E. = [ZMp + (A - Z)Mn - M(A, Z)]c2
2. B.E. = [ZMp + AMp - M(A, Z)]c2
3. B.E. = M(A, Z) - ZMp - (A - Z)Mn
4. B.E. = [M(A, Z) - ZMp - (A - Z)Mn]c2

Two radioactive substances A and B have decay constants 5 and respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be ( 1e )2 after a time interval

1. 4
2. 2
3. 12
4. 14

In a radioactive decay process, the negatively charged emitted -particles are

1. the electrons produced as a result of the decay of neutrons inside the nucleus
2. the electrons produced as a result of collisions between atoms
3. the electrons orbiting around the nucleus
4. the electrons present inside the nucleus

If the nucleus 2713Al has a nuclear radius of about 3.6 fm, then 12552Te would have its radius approximately as

1. 9.6 fm
2. 12.0 fm
3. 4.8 fm
4. 6.0 fm

The binding energy of deuteron is 2.2 MeV and that of 42He is 28 MeV. If two deuterons are fused to form one 42He then the energy released is

1. 30.2 MeV
2. 25.8 MeV
3. 23.6 MeV
4. 19.2 MeV

In a radioactive material the activity at time t1 is R1 and at a later time t2, it is R2. If the decay constant of the material is , then

1. R1 = R2
2. R1 = R2 e- (t1 - t2)
3. R1 = R2 e (t1 - t2)
4. R1 = R2(t2/t1).

The radius of germanium (Ge) nuclide is measured to be twice the radius of 94Be. The number of nucleons in Ge are

1. 72
2. 73
3. 74
4. 75

In the reaction 21H + 31H 42He + 10n, if the binding energies of 21H, 31H and 42He are respectively a, b and c (in MeV), then the energy (in MeV) released in this reaction is

1. a + b + c
2. a + b - c
3. c - a - b
4. c + a - b