Question

in this passage, scientist richard feynman explains how uranium can be used to create an atomic bomb. select the best evidence to support the statement that u - 235 is rare. feynman explained the basics: how uranium atoms split when hit with neutrons, how they give off energy, how a chain reaction could lead to an explosion. it wouldnt work with just any uranium, though. the nucleus of a uranium atom usually had a total of 238 protons and neutrons. it’s called u - 238. when hit with a speeding neutron, u - 238 does not fission. it’s useless to bomb makers. but a small percentage of uranium atoms—about 1 out of every 130—have a total of 235 protons and neutrons. this is u - 235. when u - 235 is hit by neutrons, it does split and release energy. from steve sheinkin, bomb: the race to build—and steal—the world’s most dangerous weapon. copyright 2012 by steve sheinkin

Explanation:

To support that U - 235 is rare, we look for evidence about its proportion. The passage says "a small percentage of uranium atoms - about 1 out of every 130 - have a total of 235 protons and neutrons. This is U - 235." This shows that U - 235 is a small fraction (1 in 130) of uranium atoms, indicating rarity.

Answer:

The best evidence is: "But a small percentage of uranium atoms - about 1 out of every 130 - have a total of 235 protons and neutrons. This is U - 235."