Physics nuclear fuel help me check answer please?

Question

1 ) If gold were used as nuclear fuel, it would be best

a. fissioned.

b.either fused or fissioned.

c. fused. (answer)

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2) If uranium were split into three equal segments instead of two, the reaction would be

a. more energetic.

b. as energetic.

c. less energetic.

d. not enough information is given for a reasonable estimate. (asnwer)

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3) Could you get rid of plutonium contaminating a soil sample by bombarding it with neutrons?

a. No.

b. Not enough information is given. (answer)

c. Yes, but you might not like what you got in its place.

4) In massive stars, three helium nuclei can fuse together, forming a carbon nucleus. This reaction heats the core of the star. The net mass of the three helium nuclei must therefore be

a. higher than that of the carbon nucleus.

b. less than that of the carbon nucleus.

c. the same as that of the carbon nucleus (mass is always conserved). (Answer)

Answer 1

1. A. Fissioned, anything with a higher atomic number than Fe-56 would have to be fissioned.  See the binding energy curve.  http://en.wikipedia.org/wiki/Image:Bindi...

2. A, based on the binding energy curve above.  You will convert more mass into energy by dividing into three pieced instead of 2.  You can also check this with seeing the mass of the nuclei of U-235 and the pieces it would break up into.

3. C, plutonium would both fission and capture the neutrons if you bombarded it with enough of them.

4. A. Since you get energy out of the reaction, that means that the mass of the 3 Helium nuclei is more than that of one carbon nucleus.  This does not violate the conservation principle since you get the energy out of it.