Question

If 20 cc of methane is burnt using 50 cc of oxygen, the volume of the gases left after cooling to room temperature will be:

• A. 60 cc
• B. 70 cc
• C. 30 cc
• D. 50 cc

Answer 1

The correct option is C 30 cc

Balanced chemical reaction:

$C{H}_4+2O_2\to C{O}_2+2H_{2}O$

• Here, from the equation, we conclude that 2 c.c of $O_2$ is required to burn 1 cc of methane.
• 20 cc of methane is completely burnt using 50 cc of oxygen.
• 20 cc of methane will react with 40 c.c of oxygen to give 20 cc of carbon dioxide and liquid water. $10$ c.c of oxygen will remain.

• The volume of the gas left after cooling to room temperature is $10+20cc=30cc.$

Hence , option C is correct .