True color in water can be caused by which of the following?

• A. Organic materials like fuels/oils/dyes or inorganic materials like iron and copper.
• B. Only organic materials such as fuels or oils.
• C. Only inorganic metals like iron and copper.
• D. Distilled water with no impurities.

Answer: (A)

True color in water comes from substances that are dissolved or finely dispersed and that absorb certain wavelengths of light, giving the water its tint. Organic materials such as fuels, oils, or dyes have chromophores in their molecules that absorb visible light and impart color to water. Inorganic metals, like iron and copper, form colored ions or compounds in water, which also produce colored hues (iron often yields yellow-brown tones, while copper can give blue-green). Distilled water with no impurities is essentially colorless because there’s nothing dissolved to absorb light. So, both organic materials and inorganic metals can cause true color, making the combined option the best choice.