Question

5g of Ca combine with 2g of oxygen to form a compound. Find the molecular formula of the compound

Answer 1

4.5g of Calcium oxide(CaO)

Answer 2

the reaction will always have same ratio of calcium and oxygen . so , if 5:2 of calcium and oxygen after reaction forms calcium oxide then 15:6 of calcium and oxygen will react to form calcium oxide. 6g oxygen reacting with 15g of calcium will form 21g of calcium oxide.