(i) The peculiar smell observed near the preserved specimens in biology laboratory is due to formalin. Formalin is the aqueous solution of formaldehyde and has pungent smell. (ii) When methanol reacts with hydrogen cyanide, a molecule of H—CN is added across the carbon-oxygen double bond of methanol. Hence, addition reaction occurs. (iii) Propanone can be used as a nail polish remover as it is a colourless and volatile liquid and acts as a good organic solvent.