You are given 18.6 g of mg. do you have a mole of magnesium.

No, 18.6 g of Mg contain 0.765 mole.

Given that,

amount of Mg we have = 18.6

By looking at periodic table:

Molar mass of magnesium = 24.305 u (g/mole)

It means one mole of magnesium contain 24.305 grams of magnesium

So,

24.305g = 1 mole

1g = 0.04114379757 mole

18.6g = 0.765 mole

Hence, 18.6 g of Mg contains 0.765 mole

             24.305 g of Mg contains a mole of Mg.

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.