a) state the number of atoms of each element present.
b) give the total number of atoms present in each compound.

According to the Law of Definite Proportions from Dalton's Atomic Theory, each compound is composed of a fixed ratio of each of its individual elements. So, the number of individual elements per 1 particle of that compound is represented by the subscripts. The answers are as follows:

Table sugar: 12 atoms of carbon, 22 atoms of hydrogen; 11 atoms of oxygen; 45 total atoms
Marble: 1 atom of calcium, 1 atom of carbon; 3 atoms of oxygen; 5 total atoms
Natural gas: 1 atom of carbon, 4 atoms of hydrogen; 5 total atoms
Rubbing alcohol: 3 atoms of carbon, 8 atoms of hydrogen; 1 atom of oxygen; 12 total atoms
Table sugar: 1 atom of silicon; 2 atoms of oxygen; 3 total atoms

Iwould google this

It is 4.92 e-4 sorry if i am wrong