Flow Scheme of Functional Group Tests -- I?

Question

In terms of the flow-scheme for the identification of unknowns, which of the following test sequences would be appropriate for 3-pentanone?

1) Chromic acid - Iodoform
2) 2,4-Dinitrophenylhydrazine - Tollens - Iodoform
3) 2,4-Dinitrophenylhydrazine - Chromic acid - Iodoform
4) Iodoform

anyone has any idea?thank you

Answer 1

2 would tell you, in order,
carbonyl compound
ketone,
not in position 2.

Therefore, if you knew it had 5 x C atoms, it has to be pentan-3-one.