Match the reaction in List-I with the mechanism followed by them in List-II and choose the correct option. 

Column I		Column II
(P)	$C_6{H}_{5}CHO$	(I))	Gives iodo form test
(Q)	$C{H}_3-C\equiv CH$	(II)	Gives precipitate with 2,4-DNP test
(R)		(III)	$AgN{O}_3/N{H}_{4}OH$
(S)	$C{H}_{3}C{H}_{2}OH$	(IV)	Gives neutral $FeC{l}_3$ test

Choose the correct answer from the options given below.