Answer:

Explanation:
First reaction gives you the number of moles or the mass from Carbon and hydrogen
for carbon:


Analogously for hydrogen:
0.0310g
have 0.0034gH or 0.0034mol of H
In the second reaction you can obtain the amount of nitrogen as a percentage and find the mass of N in the first sample.

now

this is equivalet to 0.002mol of N
with this information you can find the mass of oxygen by matter conservation.

this is equivalent to 0.004molO
finally you divide all moles obtained between the smaller number of mole (this is mol of H)

and you can multiply by 5 to obtain: 
Answer:
The answer is: <u>Al2O3</u>
Explanation:
The data they give us is:
To find the empirical formula without knowing the grams of the compound, we find it per mole:
- 0.545 g Al * 1 mol Al / 27 g Al = 0.02 mol Al
- 0.485 g O * 1 mol O / 16 g O = 0.03 mol O
Then we must divide the results obtained by the lowest result, which in this case is 0.02:
- 0.02 mol Al / 0.02 = 1 Al
- 0.03 mol O / 0.02 = 1.5 O
Since both numbers have to give an integer, multiply by 2 until both remain integers:
Now the answer is given correctly:
Every 2 million years the amount is halved
0 million = 200g
2 million = 200g/2 = 100g
4 million = 100g/2 = 50g
6 carbon atoms
H H
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3 x H - C - C - O - H
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H H