If you’re referring to stoichiometry, which usually involves the long t-tables of multiple conversions, then you’re not alone in wondering the purpose of using them. The purpose of conversion tables is to help keep track of what you’re doing. When quickly converting one value to another, it’s very easy to forget a particular piece to the puzzle, or to use a factor that doesn’t work for that instance. Teachers usually draw out a t-table every time they work a problem so as not to confuse students, but anytime you’re working with funky units or converting across systems (metric to imperial and vice versa) it’s a good idea to use them.
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: 
Pairs of electrons are shared between two nonmetal atoms
hope this helps (:
Answer:
It get thicker beacause the mid ocean
Explanation:
Because when it gets moved back the heat rises and it builds up to be thicker.