Three colourless liquids with the following formulae are in separate unlabelled bottles: $\text{CH}_3\text{CH}_2\text{CO}_2\text{H}$, $\text{CH}_3\text{CH(OH)CO}_2\text{H}$, $\text{CH}_3\text{COCO}_2\text{H}$. Which two tests, done on separate portions of each liquid, would allow each liquid to be identified successfully?
- Atest 1: $\text{NaHCO}_3$; test 2: 2,4-DNPH reagent
- Btest 1: $\text{NaHCO}_3$; test 2: Tollens' reagent
- Ctest 1: warm acidified dichromate; test 2: 2,4-DNPH reagent
- Dtest 1: warm acidified dichromate; test 2: Tollens' reagent