Step 5: Measure the Mass of the Water (Iron)
12.42 g
52.66 g
40.24 g ?

Here's link to the

tinyurl.com/wtjfavyw

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.

i believe the answer is three water molecules