CBSE
Multiple Choice QuestionsThe activity of a radioactive sample decreases to
(1/3)rd of its original value in 3 days. Then, in 9 days its activity will become
(1/27) of the original value
(1/9) of the original value
(1/18) of the original value
(1/3) of the original value
Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called
gamma camera
CAT scan
radiotracer technique
gamma ray spectrosccopy
Assertion: Quasar emits radiowaves more than radio galaxy.
Reason: Quasar has very small size
If both the assertion and reason are true and reason is a correct explanation of the assertion.
If both assertion and reason are true but assertion is not a correct explanation of the assertion.
If the assertion is true but the reason is false.
If both assertion and reason are false.
In a material medium, when a positron meets an electron both the particles annihilate leading to the emission of two gamma ray photons. This process forms the basis of an important diagnostic procedure called
MRI
PET
CAT
SPECT
Assertion: Radioactive nuclei emit β- particles.
Reason: Electrons exist inside the nucleus.
if both assertion and reason are true and the reason is the correct explanation of the assertion
if both assertion and reason are true and the reason is not the correct explanation of the assertion
if assertion is true but reason is false
If both assertion and reason are false statements
Assertion: Neutrons penetrate matter more readily as compared to protons.
Reason: Neutrons are slightly more massive than protons.
if both assertion and reason are true and the reason is the correct explanation of the assertion
if both assertion and reason are true and the reason is not the correct explanation of assertion
if assertion is true but reason is false
if both assertion and reason are false statements
Mass of the proton is 1840 times that of electron. It is accelerated through a potential difference of 1V. Find its kinetic energy.
6 eV
2 eV
10 eV
1 eV
A certain radioactive element has a half-life of 20 years. If we have a block with 10 g of the element in it, after how many years will there be just 2.5 g of the element in the block?
80 years
40 years
100 years
60 years
A radioactive element forms its own isotope after 3 consecutive disintegrations. The particles emitted are
3 β-particles
2 β-particles and 1α-particle
2 -βparticles and 1 γ-particle
2 α-particles and 1 β-particle
If r1 and r2 are the radii of the atomic nuclei of mass numbers 64 and 125 respectively, then the ratio (r1/r2) is
64/125
5/4
4/5
