Which of the following pairs of substances can be distinguished by use of NaHCO3 solution?

NaHCO₃ solution is commonly used as a test for carboxylic acids. When a carboxylic acid is added to NaHCO₃ solution, it reacts to produce carbon dioxide gas, water, and a sodium carboxylate salt. Therefore, the pair of substances that can be distinguished by use of NaHCO₃ solution is: - CH₃CH₂OH and CH₃COOH CH₃CH₂OH is ethanol, which is not a carboxylic acid, and therefore does not react with NaHCO₃ solution. CH₃COOH is ethanoic acid, which is a carboxylic acid, and reacts with NaHCO₃ solution to produce carbon dioxide gas. The other options cannot be distinguished using NaHCO₃ solution because they do not involve carboxylic acids.