In the nucleus of 11Na23, the number of protons, neutrons and electrons are.
11,12,0
23,12,11
12,11,0
23,11,12
A free neutron decays into a proton, an electron and.
A beta particle
An alpha particle
an antineutrino
a neutrino
Which of the following us used as a moderator in nuclear reactor?
Plutonium
Cadmium
Heavy water
Uranium
The activity of radioactive sample is measured as 9750 counts/min at t=0 and as 975 constant/min at t = 5 min. The decay constant is approximately :
0.922/min
0.691/min
0.461/min
0.230/min
The nucleus 48CD115, after two successive β-decay will give.
46Pa115
49In114
50Sn113
50Sn115
The stable nucleus that has a radius half that of Fe56 is
Li7
Na21
S16
Ca40
In radioactive decay process, the negatively charged emitted β-particles are.
the electrons present inside the nucleus
the electrons produced as a result of the decay of neutrons inside the nucleus
the electrons produced as a result of collisions between atoms
the electrons orbiting around the nucleus
The mass number of He is 4 and that for sulphur is 32. The radius of sulphur nuclei is larger than that of helium by
√8
4
2
8
Complete the equation for the following fission process:
92U235 + 0n1 → 38Sr90 + ....
54Xe143 + 3 0n1
54Xe145
57Xe142
54Xe142 + 0n1
Half - lives of two radioactive substances A and B are respectively 20 min and 40 min. Initially, the samples of A and B have equal number of nuclei. After 80 min he ratio of remaining number of A and B nuclei is.
1 : 16
4 : 1
1 : 4
1 : 1