Which of the following is not a common state symbol?

State symbols are used in chemical equations to indicate the physical state of substances at room temperature. The common state symbols include:

• (g) for gases
• (l) for liquids
• (s) for solids
• (aq) for aqueous solutions, which are substances dissolved in water.

The symbol (i) is not recognized as a standard state symbol in chemistry. Therefore, when determining which choice is not a common state symbol, (i) is the correct answer, as it does not represent any physical state of matter commonly used in chemical equations. The other options—(g), (aq), and (l)—each signify specific states of matter and are widely accepted in the field of chemistry.