A radioactive substance contains 10000 nuclei and its half-life period is 20 days. The number of nuclei present at the end of 10 days is
7070
9000
8000
7500
A radioisotope has a half-life of 5 yr. The fraction of the atoms of this material that would decay in 15 yr will be
1
2/3
7/8
5/8
A particle of mass m at rest decays into two particles of masses m1 and m2 having non zero velocities. The ratio of de-Broglie wavelengths of the particles is
m1/m2
m2/m1
1.0
In nuclear reaction
the atomic mass and number of P are, respectively:
170,69
172,69
172,70
170,70
B.
172,69
A radioactive substance has activity 64 times higher than the required normal level. If T1/2 = 2h, then the time, after which it should be possible to work with it, is:
16 h
6 h
10 h
12 h
In a mean life of radioactive sample :
about of substance disintegrates
about of substance disintegrates
about 90% of the substance disintegrates
almost all the substance disintegrates
If the half-life of any sample of a radioactive substance is 4 days, then the fraction of the sample will remain undecayed after 2 days, will be
For the stability of any nucleus:
binding energy per nucleon will be more
binding energy per nucleon will be less
no. of electrons will be more
none of these
Nuclear fusion is common to the pairs :
thermonuclear reactor, uranium based nuclear reactor
energy production in sun, uranium-based nuclear reactor
energy production in sun, hydrogen bomb
the disintegration of heavy nuclei, hydrogen bomb