Answer:

Explanation:
Given : The width of a DNA molecule = 2.5 nanometers.
A nanometer = 0.000000001 meter.
In scientific notation it will be
A nanometer =
meter
⇒ 2.5 nanometers=
meters
Therefore , the width of a DNA molecule =

We use scientific notation to express a very big or a very small number in the product of a decimal ( between 1 and 10) and powers of ten.