CBSE
Multiple Choice QuestionsA radioactive element decays into . The number of β-particles emitted are
1
2
4
6
The binding energy per nucleon is maximum in the case
The half-life of radio isotope is 4 h. If initial mass of the isotope was 200 g, then mass remaining after 24 h will be
1.042 g
2.084 g
3.125 g
4.167 g
Remaining quantity (in%) of radioactive element after 5 half lives is
4.125%
3.125%
31.1%
42.125%
The half-life of 198Au is 2.7 days. The average life is
4 days
3.4 days
3.9 days
None of the above
If MO is the mass of an oxygen isotope 8O17 Mp and Mn are the masses of a proton and a neutron, respectively, the nuclear binding energy of the isotope is
MO c2
( MO - 17Mn ) c2
(MO - 8Mp ) c2
( 8 Mp + 9 Mn - MO)
A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2 : 1. The ratio of their nuclear size will be
21/3 : 1
1 : 31/2
31/2 : 1
1 : 21/2
A block having 12g of element is placed in a room. This element is a radioactive element with half-life of 15 yr. After how many years will there be just 1.5 g of the element in the box?
40 yr
45 yr
20 yr
15 yr
A7 Li target is bombarded with a proton beam current of 10-4 A for one hour to produce 7Be of activity 1.8 × 108 disintegrations per second. Assuming that one 7Be radioactive nuclei is produced by bombarding 1000 protons, its half-life is
0.87 × 107 s
0.2 × 107 s
0.67 × 108 s
0.87 × 106 s
Two radioactive materials X1 and X2 have decay constants 6 and 3A 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 after a time
