Just as some chemicals must be given activation energy to start ...

[yoroshambo]

Just as some chemicals must be given activation energy to start an exothermic chemical reaction, some nuclei must be given nuclear activation energy in order to undergo an exothermic fission.
 
  What will be an ideal response?

Question 2

Substantial heat transfer by conduction can occur over great distances.
 
  What will be an ideal response?

[jaykayy05]

Answer to Question 1

This is the case. In most cases, a neutron enters the nucleus and bangs about,
setting the nucleus into oscillation like a drop of liquid. Eventually, the nucleus comes apart.
This makes extra neutrons that can go on to break up other nuclei.

Answer to Question 2

The veracity of the answer depends on the student's interpretation of great
distance. A student might cite, for example, conduction from Earth's core to Earth's
surface, which takes place over thousands of kilometers. However, this is not the common
experience; more likely is for the student to think about conduction from soup to fingers
through a metal spoon. In the latter case, we will excuse the student from thinking that
conduction is a short-distance phenomenon. I would grade the student on the reasoning
exhibited rather than the answer.

[yoroshambo]

Excellent

[nguyenhoanhat]

Thanks for the timely response, appreciate it