When you add sodium hydrogen carbonate to acetic acid in a test tube, a gas liberates immediately with a brisk effervescence. Name the gas and describe the method of its testing in the laboratory.

(a) Oxygen; It can be tested using a glowing splint.
(b) Carbon dioxide; It can be tested using limewater, which turns milky.
(c) Hydrogen; It can be tested using a burning splint, which produces a "pop" sound.
(d) Nitrogen; It can be tested using a glowing splint.