Search any question & find its solution
Question:
Answered & Verified by Expert
Assertion : It is desirable to slow down fast moving neutrons to sustain controlled chain reactions.
Reason : Slow moving neutrons efficiently collides with $\mathrm{U}^{235}$.
Options:
Reason : Slow moving neutrons efficiently collides with $\mathrm{U}^{235}$.
Solution:
2821 Upvotes
Verified Answer
The correct answer is:
If assertion is true but reason is false.
The average energy of a neutron produced in fission of $\mathrm{U}^{235}$ is $2 \mathrm{MeV}$. These neutrons unless slowed down will escape from the reactor without interacting with uranium nuclei, unless a large amount of fissionable material is used for sustaining the chain reaction. What we needs to do is to slow down the fast neutrons by elastic scattering with light nuclei. Chadwick's experiment showed that in an elastic collision with hydrogen neutron almost come to rest.
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.