CBSE
Multiple Choice QuestionsWhen an electron-positron pair annihilates, the energy released is about
0.8 × 10-13 J
1.6 × 10-13 J
3.2 × 10-13 J
4.8 × 10-13 J
Assertion: Cobalt-60 is useful in cancer therapy.
Reason: Cobalt-60 is a source of y-radiations capable of killing cancerous cells.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements
According to Hubble's law, the redshift (Z) of a receding galaxy and its distance r from earth are related as
Z ∝ r
Z ∝ 1/r
Z ∝ 1/r2
Z ∝ r3/2
The magnetic moment ( μ) of a revolving electron around the nucleus varies with principal quantum number n as
μ ∝ n
μ ∝ 1/n
μ ∝ n2
μ ∝ 1/n2
If alpha, beta and gamma rays carry same momentum, which has the longest wavelength?
Alpha rays
Beta rays
Gamma rays
None, all have same wavelength
Assertion: The number of electrons in a p-type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature.
Reason: It is due to law of mass action.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Assertion: The binding energy per nucleon, for nuclei with atomic mass number A > 100 decreases with A.
Reason: The nuclear forces are weak for heavier nuclei.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements
A nucleus of mass number A, originally at rest, emits on -particle with speed v. The daughter nucleus recoil with speed a speed
Assertion: It is not possible to use 35Cl as the fuel for fusion energy.
Reason: The binding energy of 35Cl is too small.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
A radioactive material has a half-life of 10 days. What fraction of the material would remain after 30 days?
0.5
0.25
0.125
0.33
