20 mL of methane is completely burnt using 50 mL of oxygen. The volume of the gas left after cooling to room temperature is

Options

A. 80 mL
B. 40 mL
C. 60 mL
D. 30 mL

Answer

D

Explanation

`CH_(4) + 2HO_(2) to CO_(2) + 2H_(2)O`
1 mol methane reacts with 2 mol of oxygen to give 1 mol of `CO_(2)` i.e., 1 mL of methane reacts with 2 mL of oxygen to give 1 mL of `CO_(2)` , 20 mL of methane reacts with 40 mL of oxygen to give 20 nL of `CO_(2)`
Vol. of oxygen left = 10 mL
Vol.of `CO_(2)` formed = 20 mL
Total volume = 30 mL