Therefore, the answer is: colorless crystal at room temperature; Phenol may react chemically with gases in the air; Phenol is corrosive, so care should be taken to avoid contact with skin when using it (reasonable);
(2) When the activated carbon is put into purified water to adsorb phenol, no new substance is produced, which is a physical change;
So the answer is: physics;
(3) Whether the treated water in the waterworks belongs to hard water can be detected by soapy water: if there are many foams, it is soft water; If there are more scum and less foam, it is hard water;
So the answer is: soapy water;
(4) Specific methods to prevent water pollution include: discharging industrial wastewater up to standard, rationally using pesticides and fertilizers, and not using phosphorus-containing detergents;
So the answer is: industrial wastewater is discharged after reaching the standard? (as long as it is reasonable)