Draw lots for invigilation of senior high school entrance examination.

(1) A balance with medicine and indicating that a certain amount of solid medicine needs to be weighed, a measuring cylinder and a beaker, and a rubber-tipped dropper indicating that water needs to be taken, so the name is to prepare a solution with a certain solute mass fraction;

(2) The instruments needed to prepare the solution are: tray balance, rubber-tipped dropper, beaker, measuring cylinder and glass rod, so there are few glass rods;

(3) The bottle stopper should be inverted on the desktop, otherwise the medicine on the bottle stopper will corrode the desktop and pollute the reagent; Weighing drugs should be divided into left-handed and right-handed, otherwise the weighing quality is small;

(4) The original plan cannot be calculated according to the wrong operation. The weight plus running code is 18g, and the water is 82g, so the mass fraction is:18g+82g×100% =18%.

So the answer is: (1) prepare a solution with a certain solute mass fraction; (2) glass rod; (3) The bottle stopper of the reagent is not inverted; When weighing, the weight and salt are inverted; (4) 18%.