balance the following chemical questions

1.sno2+h2--> sn+h2o

2.fes+o2--> fe2o3+so2

3. c2h6o+o2--> co2+h2o

4.agi+na2s--> ag2s+nai

Which of these statements describes the size of an atom? a. an atom is larger than a sheet of aluminum foil. b. an atom is small but can be seen with just our eyes. c. an atom is the size of a plastic building block. d. an atom is tiny and cannot be seen without magnification.