How many moles of sulfur are in 23.2 g of (c3h5)2s?
how many atoms of hydrogen are in 0.75 moles of (c3h5)2s?
how many grams of carbon are in 4.20*10^23 molecules of (c3h5)2s?
how many atoms of carbon are in 15.0 g of (c3h5)2s?

1)
We have 6 moles of C (2 x3=6), 10 moles of H (2 x 5=10) and 1 mole of S in 1 mole of (C₃H₅)₂S )

The molar mass of (C₃H₅)₂S is 114 g mol

atomic mass (C)=12 u
atomic mass (H)=1 u
atomic mass (S)=32 u

atomic weight ((C₃H₅)₂S )=2[3(12 u)+5( 1 u)]+32 u=114 u

molar mass=value of atomic weigth expres in g/ 1 mol
molar mass ((C₃H₅)₂S )=114 g/mol

we have to find the number of moles  in 23.2 g of (C₃H₅)₂S )
114 g1 mol
23.2 g  x

x=(23.2 g x 1 mol)/114 g≈0.2 moles

We calculate the number of moles of sulfur (S) in 23.2 g (≈0.2 moles) of (C₃H₅)₂S ).

1 mole of (C₃H₅)₂S ) 1 mole of S
0.2 moles of (C₃H₅)₂S )    x

x=(0.2 moles of (C₃H₅)₂S ) x 1 mole of S)/1 mole of (C₃H₅)₂S )=0.2 moles

we have 0.2 moles of sulfur in 23.2 gr of (C₃H₅)₂S )

2)
1 mole of any substance=6.022 x 10²³ atoms or molecules.
We have 10 moles of H in a mole of (C₃H₅)₂S )

1 mole of  (C₃H₅)₂S )10 moles of H
0.75 moles of (C₃H₅)₂S )  x

x=( 0.75 moles  x  10 moles)/1 mole=7.5 moles

We compute the number of atoms in 7.5 moles of H

1 mole 6.022 x 10²³ atoms
7.5 moles    x

x=(7.5 moles x  6.022 x 10²³ atoms)/1 mole=4.52 x 10²⁴ atoms.

we have 4.52 x10²⁴ atoms of H in 0.75 moles of (C₃H₅)₂S )

3)
We have to calculate the number of moles in 4.20 x 10²³molecules of (C₃H₅)₂S )

1 mole6.022 x 10²³ molecules
x4.20 x 10²³ molecules

x=(1 mole x 4.20*10²³)/6.022*10²³ molecules≈0.697 moles

we have 72 g of C in 1 mole of (C₃H₅)₂S ).
number of grams in 1 mole of  (C₃H₅)₂S )=2*3*12 g=72 g

1 mole of (C₃H₅)₂S )72 g of C
0.697 moles of (C₃H₅)₂S )      x

x=(0.697 moles * 72 g)/1 mole≈50.18 g

there are 50.18 g of C in 4.20*10²³ molecules of (C₃H₅)₂S )

4)
We have to calculate the number of moles in 15 g of (C₃H₅)₂S )
 
114 g of (C₃H₅)₂S ) 1 mole of (C₃H₅)₂S )
15 g of (C₃H₅)₂S )   x

x=(15 g * 1 mole)/114 g=0.1316 moles of (C₃H₅)₂S )

We calculate the number of moles of C in 0.1316 moles of (C₃H₅)₂S )

1 mole of (C₃H₅)₂S )6 moles of C
0.1316 moles of (C₃H₅)₂S )   x

x=(0.1316 moles * 6 moles)/1 mole=0.7895 moles

We calculate the number of atoms in 0.7895 moles of C

1 mole of C 6.023*10²³ atoms of C
0.7895 moles of C    x

x=(0.7895 moles * 6.022*10²³)/1 mole≈4.75*10²³ atoms.

there are 4.75*10²³ atoms of C in 15 g of (C₃H₅)₂S )

Other way:
We calculate the number of molecules in 15 g of (C₃H₅)₂S )
114 g of (C₃H₅)₂S )6.023*10²³ molecules of (C₃H₅)₂S )
15 g of (C₃H₅)₂S )x

x=(15 g* 6.022*10²³ molecules)/114 g=7.9237 *10²² molecules

A molecule of (C₃H₅)₂S ) have 6 atoms of C; therefore
1 molecule6 atoms of C
7.9237 *10²² molecules    x

x=(7.9237*10²² molecules * 6 atoms)/1 molecule=4.75*10²³ atoms

We have the same there are 4.75*10²³ atoms of C in 15 g of (C₃H₅)₂S )