plz i really need help in this chemistry questions?

Question

1. A 0:32 g sample of H2O contains how many
molecules of water? Answer in units of molec.


2. How many grams do 3:6£1023 atoms of mag-
nesium weigh? Answer in units of g.


3. How many molecules of aspirin (C9H8O4) are
there in a 150 mg tablet of aspirin? Answer
in units of molec.



5. How many atoms of carbon are present in
54:8 g of a compound that is 23:3% carbon,
by weight? Answer in units of atoms.



tell me how hyou do iit or jus thte answer even.

Answer 1

First I am having a bit of problem with your notation.

Assuming for # 1
0.32g H2O/18 x 6.02E23 = 1.07E22 atoms

Number 2
3.6E23/56.02E23 x24.305 = 14.5g

Number 3
0.150/180 x6.02E23 = 5.02E20

Number 5
54.8x 0.233/12 x6.02E23 = 6.41E23

Note: E = 10^ for example Avogadro's number = 6.02E23 or 6.02 x 10^23

P. S. Where is number 4?