What is the radius of iodine atom? (atomic No.53, Mass No.126)
2.5 × 10-11 m
2.5 × 10-9 m
7 × 10-9 m
7 × 10-6 m
The constituents of atomic nuclei are believed to be
neutrons and protons
protons only
electrons and protons
electrons, protons and neutrons
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
Solar energy is due to
fusion reaction
fission reaction
combustion reaction
chemical reaction
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 is used as a moderator in nuclear reactors?
Plutonium
Cadmium
Heavy water
Uranium
Alpha particles are
2 free protons
helium atoms
singly ionized helium atoms
doubly ionized helium atoms
The mass density of a nucleus varies with mass number A as
A2
A
constant
1/A
Energy released in the fission of a single 92U235 nucleus is 200 MeV. The fission rate of a 92U235 filled reactor operating at a power level of 5 W is
1. 56 × 10-10 s -1
1. 56 × 1011 s-1
1. 56 × 10-16 s-1
1. 56 × 10 -17 s-1
The binding energy per nucleon is maximum in case of
2He4
26Fe56
56Ba141
92U235