In order to adequately control the chain reaction in a nuclear power plant, it is necessary to have within the fissionable material a non-fissionable material that neutrons.
a. contributes
b. absorbs
c. reflects
d. emits
e. slows down

B

Explanation:

In a chain reaction of radioactive decay, more and more neutrons are produced that bombard more nuclei causing them to split (decay). This how a nuclear core releases more and more energy. The purity of the radioactive core determines the chain reaction and rate of energy released. A few impurities (nonfissionable material) are introduced to absorb excess  neutrons (and regulate their numbers) to prevent overheating of the core.

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

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