If a colourless liquid with a pungent odour is added slowly to another colourless liquid, a dark brown precipitate is produced that later dissolves to produce a colourless solution.

What are the two colourless liquids?

To determine the two colorless liquids involved, we need to analyze the information given.

First, we know that when the two liquids mix, a dark brown precipitate is formed. This indicates the occurrence of a chemical reaction, which typically involves the formation of a solid product (precipitate) when two aqueous solutions are combined.

Next, we are informed that the dark brown precipitate later dissolves to produce a colorless solution. This suggests that the initial formation of the precipitate might be reversible, indicating a dynamic equilibrium between the solid precipitate and the dissolved species.

Given these observations, it is likely that the two colorless liquids involved are:

1. A colorless liquid containing a dissolved metal cation, such as a metal salt. The metal cation could be any metal that forms a dark brown precipitate with certain reactants, such as iron (Fe), copper (Cu), or manganese (Mn).

2. A colorless liquid containing an anion or reactant that can form a dark brown precipitate when reacted with the metal cation in the first liquid. This anion could be any negatively charged species, such as a chloride ion (Cl-), a sulfate ion (SO42-), or a carbonate ion (CO32-).

Since the question does not provide specific details about the identity of the two liquids, these are general possibilities based on the given information. Further information would be needed to determine the exact nature of the liquids involved.