Question

Class X Sciences
[papers from previous years]

A student takes 2 mL acetic acid in a dry test tube and adds a
pinch of sodium hydrogen carbonate to it. He makes the following
observations:

I. A colourless and odourless gas evolves with a brisk
effervescence.
II. The gas turns lime water milky when passed through it.
III. The gas burns with an explosion when a burning splinter is
brought near it.
IV. The gas extinguishes the burning splinter that is brought
near it.

The correct observations are:

(A) I, II, and III
(B) II, III and IV
(C) III, IV and I
(D) IV, I and II

Answer 1

The answer is d............

Answer 2

when acetic acid react with sodium hydrogen carbonate it produce carbon dioxide gas with effervescence. 
and carbon dioxide is colourless, turns lime water milky, use as extinguishes.
so the answer is D