nucleus question

Question

which type of nucleus will mostly likable be unstable

 

a.  small nucleus with few protons or neutrons

b.  large nucleus with many protons and neutrons

c.  a nucleus where the strong force between the protons is stornger than their repulsive force

d.  all of these

e.  none of these

 

 

when the nucleus of uranium 234 istope is struck with a neutorn

 

a.  the nucleus splits and energy and newutrons are released

b.  the nucleus fuses with other nuclei and energy is released

c.  meltdown occurs

d.  plasma is created

 

 

thanks

Answer 1

1: B. 

 

Large nuclei tend to be unstable. Notice that all the elements heavier than lead are radioactive for all their isotopes. One way to explain this is that the strong (attractive) force between protons only acts at a small distance, while the electrostatic (repulsive) force between protons is still present at a far distance.

 

The other two answers can be eliminated as follows:

1. (A) Small nuclei are only unstable if the number of protons and the number of neutrons do not match a certain fit (small nuclei usually have one or two more neutrons than protons). But very large nuclei are always unstable.
2. (C) Nuclei in which the strong force overwhelms repulsive forces are naturally stable. This means that the nuclei "want to stay together" more than they "want to break apart".

 

 

2: A

 

This can be found true by elimination.

1. (B) Uranium-234 is already too large. Fusing with other nuclei would only make it less stable.
2. (C) Meltdown refers to overheating in a nuclear reactor that causes systemic failure. This has more to do with reactor maintenance and construction than with nuclear physics itself.
3. (D) Plasma is generated when gaseous atoms are heated/polarized sufficiently so that their valence electrons break lose and become conduction electrons. This is an irrelevant answer.