HELPPP a. list the following from the smallest atomic size to the largest atomic size.

Na, Ca, Si, Cl

b) mutualism

hope this : )

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

d) a person who learns about the world by observing it.

explanation:

scientist are people who discover why and how things are done and made in the world.