Scientific notation is often used to express numbers. when is scientific notation more appropriate than standard notation?
a) for numbers that contain fractions.
b) for very large or very small numbers.
c) for measured values during experiments.
d) for numbers and computations during science class.

When you have very large or small numbers.  

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.