A radioactive element has half-life period 800 yr. After 6400 yr what amount will remain?
1/2
1/16
1/8
1/256
If the binding energy per nucleon in 3Li7 and 2He4 nuclei are respectively 5.60 MeV and 7.06 MeV, then the energy of proton in the reaction 3Li7+ p → 2 2He4 is
19.6 MeV
2.4 MeV
8.4 MeV
17.3 MeV
Which of the following is used as a moderator in nuclear reactors?
Plutonium
Cadmium
Heavy water
Uranium
The average binding energy of a nucleon inside an atomic nucleus is about
8 MeV
8 eV
8 J
8 erg
In a fission reaction
the binding energy per nucleon of X and Y is 8.5 MeV whereas of 236U is 7.6 MeV. The total energy liberate will be about
2000 MeV
200 MeV
2 MeV
1 KeV
Which of the following statements is true for nuclear forces?
They obey the inverse square law of distance.
They obey the inverse third power law of distance.
They are short range forces.
They are equal in strength to electromagnetic forces.
The mass density of a nucleus varies with mass number A as
A2
A
constant
1/A
The constituents of atomic nuclei are believed to be
neutrons and protons
protons only
electrons and protons
electrons, protons and neutrons
The half-life of radium is 1600 yr. The fraction of a sample of radium that would remain after 6400 yr is
1/4
A radioactive sample with a half-life of 1 month has the label: ‘Activity = 2 microcurie on 1 – 8 – 1991’. What would be its activity two months earlier?
1.0 microcurie
0.5 microcurie
4 microcurie
8 microcurie
