What chemical tests are appropriate to identify Butanoic acid, Propanal and 2-methyl propan-2-ol?

Firstly, to identify butanoic acid, adding a small amount of NaHCO₃ or any metal carbonates would allow effervescence tobe produced. The effervescence produced is CO₂ . To make sure the gas is CO₂, simply bubble the gas through limewater and if it goes cloudy, it indicates that the gas is CO_2.and a carboxylic acid group is present. Secondly, to test for propanal, add Tollen's Reagent to the sample and the result will be that a silver mirror is produced. Indicates that an aldehyde group is present. Finally, to test for 2- methyl propan-2-ol, heat the sample under reflux with acidified potassium dichromate. Here, there will be no colour change and hence will remain orange. This will show that the sample is a tertiary alcohol.