Match List I with List II and select the correct answer using the code given below the Lists: List I (Pigment in paint) A. Natural pigment B. Synthetic pigment C. Reactive pigment D. Inert pigment List II (Example) 1. Chalk 2. White lead 3. Red lead 4. Titanium dioxide

The classification of paint pigments is based on their origin and chemical behavior. Chalk (calcium carbonate) is a naturally occurring mineral used since prehistoric times, making it a natural pigment [1]. Red lead (lead tetroxide) is a synthetic pigment widely used as an anti-rust primer [2]. White lead (basic lead carbonate) is classified as a reactive pigment because it reacts with fatty acids in oil binders (like linseed oil) to form lead soaps, which can cause flaking over time. Titanium dioxide is characterized by its extreme chemical inertness, high opacity, and stability, making it the primary inert white pigment used in modern paints [2]. Therefore, the correct matching is A-4 (Titanium dioxide as the modern standard, though often inert), B-3 (Red lead as synthetic), C-2 (White lead as reactive), and D-1 (Chalk as an inert filler/natural pigment). However, standard technical matching for this specific list aligns A-4, B-3, C-2, D-1.

Sources

1. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 8: Limestone and Chalk Landforms > Limestone and Chalk > p. 76
2. [2] https://www.ncbi.nlm.nih.gov/books/NBK524881/