10 ml of ethanoic acid was taken in two test tubes I and II each. Blue and Red litmus papers were dipped into test tube I and solid sodium hydrogen carbonate was added to test tube II.

The following observations were reported :

i) Red litmus turned blue in I and no change was observed in II

ii) Blue litmus turned red in I and brisk effervescence was observed in II.

iii) Red litmus turned blue in I and a gas of odour like vinegar evolved in II.

iv) Blue litmus turned red in I and a gas which supports combustion evolved in II.

Which observation correctly represents the characteristics of ethanoic acid