(A) The identification tests are as follows:
$(1)$ Phenol and Carboxylic acid:
| $Test$ | $Phenol$ | $Carboxylic \text{ } acid$ |
| $NaHCO_3$ test | No reaction | Effervescence of $CO_2$ gas |
| Neutral $FeCl_3$ test | Violet/Green colour | Buff-coloured precipitate |
$(2)$ Formic acid and Acetic acid:
- Formic acid $(HCOOH)$ gives Tollen's test (silver mirror) and reduces $HgCl_2$ to white precipitate of $Hg_2Cl_2$,whereas acetic acid does not.
$(3)$ Acetic acid and Ethanol:
- Acetic acid gives effervescence with $NaHCO_3$,while ethanol does not.
- Ethanol gives the iodoform test (yellow precipitate of $CHI_3$ with $I_2/NaOH$),while acetic acid does not.
$(4)$ Acetic acid and Acetone:
- Acetic acid gives effervescence with $NaHCO_3$,while acetone does not.
- Acetone gives the iodoform test,while acetic acid does not.
$(5)$ Aldehyde and Ketone:
- Aldehydes give Tollen's test and Fehling's test,while ketones do not (except $\alpha$-hydroxy ketones).
$(6)$ Acetaldehyde and Acetone:
- Acetaldehyde gives Tollen's and Fehling's tests,while acetone does not.
- Both give the iodoform test.
$(7)$ Acetaldehyde and Formaldehyde:
- Acetaldehyde gives the iodoform test,while formaldehyde does not.
$(8)$ Benzaldehyde and Acetaldehyde:
- Acetaldehyde gives the iodoform test,while benzaldehyde does not.