Question: a. the teacher puts a sugar cube into a container of warm water. eventually the sugar cube is no longer visible. what type of change is this and why?

physical change.

Explanation:

A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.  Example: melting of ice

A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.  Example: Combustion

As the sugar cubes dissolves into a container of warm water, it only changes its state from solid to aqueous and no new substances are being formed. Thus it is a physical change.

i'd say that the moon rock is about 2.2 billion years old.

the answer is:

carbon dioxide