Which of the following symbols indicates that a substance is in aqueous (water) solution?

• A. (aq)
• B. (l)
• C. (s)
• D. (g)

Answer: (A)

Verified step by step guidance

1. Understand that in chemistry, symbols in parentheses after a chemical formula indicate the physical state of the substance.
2. Recognize the common state symbols: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solution.
3. Recall that an aqueous solution means the substance is dissolved in water, so it is in a water-based solution.
4. Identify that the symbol (aq) specifically denotes a substance dissolved in water, distinguishing it from pure liquids or solids.
5. Conclude that among the given options, (aq) is the correct symbol indicating a substance is in aqueous solution.