In an experiment, the following reaction takes place.
$C\left(s\right)+O_2\left(g\right)\to {\mathrm{CO}}_2\left(g\right)12g32g44g$
How much mass of carbon dioxide will be produced, when 12 g of carbon reacts with 48 g of oxygen?

1. 14 g

2. 10 g

3. 8 g

4. 7 g

The correct option is C

8 g

• Elements always combine together in a constant ratio by mass to form a compound.
• 12 g of carbon reacts with 32 g of oxygen, so the mass ratio is 12:32 or 3:8. 
• This means that carbon will always combine with oxygen in 3:8 by mass to form carbon dioxide.
• Hence, 12 g of carbon will combine with 32 g oxygen and produce 44 g of carbon dioxide.
• Therefore, in the given situation, 48-32 = 16 g of oxygen will be left unreacted.