Bragg's law for X-rays is:
1. dsin = 2n
2. 2dsin = n
3. nsin = 2d
4. None of these
The relationship between disintegration constant and half-life [T] will be:
1.
2.
3.
4.
Alpha particles are
1. 2 free protons
2. helium atoms
3. singly ionized helium atoms
4. doubly ionised helium atoms
A radioactive sample with a half-life of 1 month has the label: 'Activity = 2 microcurie on 1-8-1991'. What would be its activity two months earlier?
1. 1.0 microcurie
2. 0.5 microcurie
3. 4 microcurie
4. 8 microcurie
A radioactive element has half-life period 800 yr. After 6400 yr, what fraction will remain?
1.
2.
3.
4.
In a given reaction,
Radioactive radiations are emitted in the sequence of
1.
2.
3.
4.
An observer A sees an asteroid with a radioactive element moving by at a speed = 0.3 c and measures the radioactivity decay time to be . Another observer B is moving with the asteroid and measures its decay time as . Then and are related as below [VITEEE 2008]
1. <
2. =
3. >
4. Either 1 or 3 depending on whether the asteroid is approaching or moving away from A.
If a proton and anti-proton come close to each other and annihilate, how much energy will be released:
1.
2.
3.
4. None of these