Answer : The limiting reagent is 
Solution : Given,
Moles of methane = 2.8 moles
Moles of
= 5 moles
Now we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,

From the balanced reaction we conclude that
As, 2 mole of
react with 1 mole of 
So, 5 moles of
react with
moles of 
From this we conclude that,
is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Hence, the limiting reagent is 
1) protons have a positive charge
2) electrons have a negative charge
3) neutrons have a neutral charge
1 3/4 Ounces or 1.75 Ounces!
Basically 21/12 = 1.75!
(Mark me as the brainliest if this helps!)