Only solutions in water are (aq). The question should specify an aqueous solution otherwise it could be solution in alcohol, benzene or any other liquid.
Solutions are marked as (aq) and liquids as (l). If it's a solution in water it's aqueous. You can have substance as solutions in other mediums though such as ethanol, DMSO etc. If the state is not listed you can also look up the physical properties of the compound, to see if it is liquid under standard conditions.