Give simple chemical test to distinguish between the following pairs of compounds.
i. Propanal and Propanone
ii. Acetophenone and Benzophenone
iii. Phenol and Benzioc acid
iv. Benzoic acid and Ethyl benzoate
v. Pentan-2-one and Pentan-3-one
vi. Benzaldehyde and Acetophenone
vii. Ethanal and Propanal

Explanation

i. `MeCH_(2)CHO` (Propanal) (I) and `MeCOMe` (Propanone) (II).
a. Both give 2,4-DNP test.
b. (II) gives positive iodoform test, whereas (I) does not.

ii. Acetophenone `(PhCOMe)` (I) and benzophenone `(PhCOPh)` (II).
a. (I) gives positive iodoform test, (II) does not.
iii. Phenol `(PhOH)` (I) and benoic acid `(PhCOOH)` (II).
a. (II) gives effervescenes of `CO_(2)` with `NaHCO_(3)`, (I) does not.
`PhCOOH+NaHCO_(3)rarr PhCOONa+CO_(2)+H_(2)O`
`PhOH+NaHCO_(3)rarr` No evolution of `CO_(2)`
b. Phenol gives violet colour with netural `FeCl_(3)` solution but (II) gives buff coloured precipitate.
`3PhOH+FeCI_(3)rarr underset("Ferric phenoxide (Violet colour)")((PhO)_(3)Fe+3HCl)`
`3PhCOOH+FeCI_(3)rarr underset("Ferric benzoate (Buff ppt.)")((PhCOO)_(3)Fe+3HCl)`
iv. Benzoic acid `(PhCOOH)` (I) and ethyl benzoate `(PhCOOEt)` (II).
a. (I) gives `NaHCO_(3)` test [as in (iii)], but (II) doesnot.
b. (II) on boiling with excess of `NaOH` gives ethyl alcohol and sodium benzoate. Ethyl alcohol gives positive iodoform test.
`PhCOOEt+NaOH overset(Delta)rarr PhCOONa+C_(2)H_(5)OH`
`PhCOOEt+NaOH overset(Delta)rarr PhCOONa+C_(2)H_(5)OH`.

v. Penthan-2-one (I) and pentan-3-one

a. (I) gives positive Iodoform test `[(MeCO-)` group], but (II) does not.

b. (I) being a methyl ketone gives white ppt. with `NaHSO_(3)`, but (II) does not.

vi. Benzaldehyde `(PhCHO)` (I) and acetopenone `(PhCOMe)` (II).
a. (I) gives positive Tollens test, but (II) does not.
b. (II) gives positive Iodoform test `[(MeCO-)` group], but (I) does not.
`PhCHO+[Ag(NH_(3))_(2)]^(o+)OH^(Θ)rarr PhCOO^(Θ)+Ag darr`
`PhCO vdots Me underset(NaOI)rarr PhCOONa+underset("Yellow ppt.")CHI_(3)`
vii. Ethanal `(MeCHO)` (I) and propanal `(MeCH_(2)CHO)` (II).
a. (I) gives positive Iodoform test, but (II) does not.
`Me vdots CHO overset(NaOH)rarr HCOONa+CHI_(3)`