During painting, white lead is added to paint and it acts as:

The Solid Components of Paint

The solid particles in paint serve different functions. The Base is the main solid ingredient that forms the body of the paint film, providing opacity and durability. The Pigment is a solid added specifically to give color. Often, a single substance can perform both roles, but it's important to identify its primary function in the context of paint formulation.

Detailed Analysis of the Options

(a) pigment

Function: A pigment's primary role is to provide color. While white lead is a white pigment, its main contribution to paint is not just its color, but its ability to create a thick, opaque, and durable film. In paint terminology, this primary role is called the base.

(c) drier

Function: A drier is a catalyst added in small amounts to speed up the drying time of the oil-based vehicle. While some lead compounds (like lead acetate or litharge) are used as driers, white lead's primary function and main contribution is as a base, not a catalyst.

(d) carrier

Function: The carrier, also known as the vehicle or binder, is the liquid part of the paint that holds all the solid particles in suspension and forms the film upon drying. White lead is a solid powder; it is *carried by* the liquid, it is not the carrier itself.

Paint Components: Solids vs. Liquids