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
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
A.
binding energy per nucleon will be more
For the stability of nucleus, it should have high binding energy per nucleon
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