Answer:
139.11 grams
Explanation:
The molarity (M) is equal to m (moles) /L (liters).
Notice how it is in mL so converting it would be 0.75 L (750*10-3)
Now plug in the information
1.75=m/0.75
m=1.3125
Now m is in moles so convert to grams to get the mass
1.3125 mol Na2CO3 * 105.9888 g Na2CO3 = 139.1103
B. 6 atoms of carbon C
I would think this is the answer, because one can't just delete or add atoms; otherwise, the equation would be unbalanced. This also abides with the Law of Conservation of Mass.
Plus, I also came to that conclusion because if we look at the net equation of photosynthesis:

––>

The number of Carbon atoms is 6 on both the reagent's side and the product's side.
N = given mass/ molar mass.
n = number of moles
given mass = 2.47 g
molar mass = 197 g/mol
n = 2.47 / 197
n = 0.01253 moles.
I'm sure you wanted to ask more than this. Just put some comments in. I can do the same.