Question

When 3.0 gram of carbon is burnt in 8 gram of oxygen co2 is produced .what mass of CO2 is formed.

Answer 1

When 3 g of carbon is burnt in 8 g of oxygen ,we get 11g of CO2.
From this we understand that, carbon and oxygen combine in the ratio 3:8
Hence, though 3 g of carbon is burnt in 50 g of oxygen,  it will react with 8 g of oxygen only to form 11 g of carbon dioxide.

This is in accordance with law of constant proportions.