The answer for this question is niche.
which describes a term is rotation earths movement around the sun
Sublimation is when a solid turns directly into a gas, completely bypassing the liquid phase. Dry ice is a good example.
Answer: C. Z is an intermediate.
Explanation: The given reaction is 
And the rate equation is rate = k [X_2][Y]
From this, we can imply that either the concentration of Z is very small in comparison tot he other reactants or the reactant Z is an intermediate which is available only for the given small amount of time.
There can be various steps in the mechanism for the proposed reaction and Z can also react in any of the steps. It is not necessary that it should react in a step other than the rate determining step.
This might be possible that the activation energy for Z to react is very low But since it has made a new kind of product that is XZ, then the former cannot be true.
None
it is a form of electromagnetic radiation, meaning it does not have any protons or neutrons