ANS:A - Aluminium foil

Absorptivity refers to the ability of a material to absorb electromagnetic radiation, such as light. It is a property that varies depending on the material and the wavelength of the radiation. Among the options provided:

• Aluminium foil is known for its high reflectivity and low absorptivity, especially in the visible spectrum.
• Coal dust may have variable absorptivity depending on its composition and particle size.
• Refractory bricks are typically designed to withstand high temperatures and may have low absorptivity to minimize heat absorption.
• Iron plates generally have higher absorptivity compared to materials like aluminium due to their darker color and higher thermal conductivity.