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) + O_(2) to CO_(2) + 2 H_(2)O`
22400 mL of methane requires 22400 mL of oxygen for burning .
`therefore` 20 mL of methane will require = 20 mL of oxygen.
This means that 20 mL of methane will burn completely using 20 mL of oxygen .
`therefore` Volume of the gas left will be of oxygen only = (50 - 20) = 30 mL .