C or A I may be incorrect but those are what I think it is
The answer would be 5. because the last zero is a holding place because the number is in front of the decimal. They other zero counts because they are being sandwiched.<span />
Answer:

Explanation:
<u>1. Convert Grams to Moles</u>
Use the molar mass (found on the Periodic Table) to convert from grams to moles.
Use this value as a ratio.

Multiply by the given number of grams.

Flip the ratio so the grams of boron cancel out.



<u>2. Convert Moles to Atoms</u>
We use Avogadro's Number, 6.02*10²³: the number of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, the particles are atoms of boron.

Multiply by the number of moles we calculated.

The moles of boron cancel.


The original value of grams has 4 significant figures, so our answer should have the same. For the number we calculated, that is the thousandth place.

The 6 tells us to round the 2 to a 3.

25.00 grams of boron is equal to 1.393*10²⁴ atoms.
Answer:
The mass of the forest comes from carbon and carbon is retrieved from carbon-dioxide that trees used during the process of photosynthesis. In the process of photosynthesis, carbon-dioxide is utilised from the atmosphere by trees and release oxygen and ATP.
When the forest burns the mass again releases to atmosphere in the form of carbon which causes air pollution and increases carbon content in the atmosphere.