White Pigments:

White pigments are substances that are used to provide a white color to various materials such as paints, coatings, plastics, paper, and textiles. These pigments scatter and reflect light, resulting in a white appearance. There are several compounds that are commonly used as white pigments, including calcium carbonate (CaCO3), lead carbonate (PbCO3), aluminum oxide (Al2O3), and zinc oxide (ZnO).

Explanation:

The correct answer to the question is option 'D', which is zinc oxide (ZnO). Zinc oxide is widely used as a white pigment due to its excellent hiding power, light scattering properties, and high reflectivity. It has a bright white color and is often referred to as "zinc white."

Properties of Zinc Oxide:

1. Hiding Power: Zinc oxide has excellent hiding power, which means it can effectively cover the underlying surface and provide a uniform white color.

2. Light Scattering: Zinc oxide particles scatter and diffuse light, resulting in a white appearance. This property makes it an ideal pigment for achieving high opacity and brightness in paints and coatings.

3. Reflectivity: Zinc oxide has high reflectivity, which means it can reflect a significant amount of light. This property makes it suitable for use in sunscreen lotions and creams as it helps to reflect and scatter UV rays.

4. Stability: Zinc oxide is highly stable and does not easily react with other chemicals or degrade over time. This stability ensures that the white color remains intact for a longer duration.

Applications of Zinc Oxide:

Zinc oxide is extensively used in various industries and applications, including:

1. Paints and Coatings: It is a key ingredient in white paints and coatings, providing opacity and brightness.

2. Plastics: Zinc oxide is added to plastics to enhance their whiteness and provide UV protection.

3. Ceramics: It is used as a glaze in ceramic applications to achieve a white and glossy finish.

4. Rubber: Zinc oxide is used in the production of rubber products to improve their durability and appearance.

5. Cosmetics: Zinc oxide is a common ingredient in cosmetics such as foundations, powders, and sunscreens due to its UV-blocking properties.

In conclusion, zinc oxide (ZnO) is widely used as a white pigment due to its excellent hiding power, light scattering properties, high reflectivity, and stability. It finds applications in various industries, including paints, coatings, plastics, ceramics, rubber, and cosmetics.