A radioactive element has half-life period 800 yr. After 6400 yr what amount will remain?
1/2
1/16
1/8
1/256
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
Which of the following is used as a moderator in nuclear reactors?
Plutonium
Cadmium
Heavy water
Uranium
What is the respective number of α and β particles emitted in the following radioactive decay
200X90 → 168Y80?
6 and 8
6 and 6
8 and 8
8 and 6
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.
Atomic weight of boron is 10.81 and it has two isotopes and . Then, the ratio of atoms of and in nature would be
19 : 81
10 : 11
15 : 16
81 : 19
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 the ratio of remaining number of A and B nuclei is
1 : 16
4 : 1
1 : 4
1 : 1
The binding energy per nucleon is maximum in case of
2He4
26Fe56
56Ba141
92U235
The nuclei 6C13 and 7N14 can be described as
isotones
isobars
isotopes of carbon
isotopes of nitrogen
The most penetrating radiation out of the following is
γ-rays
α-particles
β-rays
χ-rays
