For question 1:
A. Carbon, hydrogen, oxygen
Calcium, carbon, oxygen
Carbon, hydrogen
Carbon, hydrogen, oxygen
Silicon, oxygen
B. Carbon: 12, hydrogen: 22, oxygen: 11
Calcium: 1, Carbon: 1, oxygen: 3
Carbon:1, Hydrogen: 4
Carbon: 3, hydrogen: 8, Oxygen: 1
Silicon: 1 oxygen: 2
C. Table sugar: 45
Marble: 5
Natural gas: 5
Rubbing alcohol: 12
Glass: 3
For question 2: N2O