Solid iodine has a colour. A. White B. Colourless C. Purple brown to slightly black D. Reddish-brown

The correct answer is C. Purple brown to slightly black.

Solid iodine is a non-metallic, lustrous, deep purple-black solid. It is a member of the halogen group and is the heaviest of the naturally occurring non-metals. Iodine is a solid at room temperature and has a melting point of 113.7 °C. It is soluble in water, but it is more soluble in ethanol and other organic solvents. Iodine is used in a variety of applications, including photography, medicine, and industry.

Option A is incorrect because solid iodine is not white. Option B is incorrect because solid iodine is not colorless. Option D is incorrect because solid iodine is not reddish-brown.