I think this the the list of choices relating to the above question.
reaction rate
<span>activation energy </span>
<span>collision theory </span>
<span>spontaneous reaction
</span>
The term that best relate to ben's observation is REACTION RATE.
Reaction rate is defined as the speed at which the chemical reaction proceeds. It either is the amount of concentration of a product in a given unit of time or the concentration of the reactant that is being consumed in a unit of time.
Answer:- 12 km = 12000 m
Solution:- It's a metric unit conversion where we are asked to convert 12 km to m where km stands for kilometer and m stands for meter.
In metric conversions, kilo means 1000.
So, 1 km = 1000 m
It means, we multiply the given km by 1000 to get the answer in m as:

= 12000 m
Hence, 12 km = 12000 m.
A hypothesis is given to explain a phenomena which has not been
explained till then.
it can be supported by an experiment if that experiment gets the other
results regarding that particular phenomena in agreement with that being
predicted by the hypothesis
C. Include changes that alter the identity of a substance.