Consider the following pairs: I. Pigment : TiO₂ II. Drier : Turpentine III. Thinner : Naphthenate IV. Anti-skinning agent : Polyhydroxy phenol. How many of the above pairs are correctly matched?

Examining each pair: (I) Pigment – TiO₂: correct, titanium dioxide is a common white pigment in paints. (II) Drier – Turpentine: incorrect; turpentine is a thinner/solvent, not a drier. Driers are typically metal naphthenates (Co, Mn, Pb). (III) Thinner – Naphthenate: incorrect; naphthenates are driers, while thinners are turpentine or mineral spirits. (IV) Anti-skinning agent – Polyhydroxy phenol: correct, polyhydroxy phenols such as hydroquinone are used as anti-skinning agents to prevent oxidation/skin formation on stored paint. Hence two pairs (I and IV) are correctly matched.