(1) The main instruments in the distillation device include distillation flask, condenser tube, horn tube, Erlenmeyer flask, and alcohol lamp. ① is the distillation flask and ② is the condenser tube. Accurate preparation of solutions requires volumetric flasks and Glass rod, ④ is a volumetric flask,

So the answer is: distillation flask; condenser tube; volumetric flask;

(2) The mercury ball of the thermometer should be level with the opening of the flask branch; separate The mixture of carbon tetrachloride and alcohol is separated by fractional distillation. In order to ensure that the water fills the condenser tube and fully condenses, the lower port of the condenser tube is the water inlet and the upper port is the water outlet, so the water inlet of the condenser tube is g ,

So the answer is: insert the mercury ball of the thermometer below the liquid surface; fractionation; g;

(3) To prepare a solution with a certain substance concentration, a glass rod must be used to drain the water to prevent When liquid splashes out, the volumetric flask has only one scale mark and can only be used to prepare solutions with the marked capacity specifications. If you need to prepare 250mL, you can only use a 250ml volumetric flask. A. When weighing, NaCl has deliquesced and n is too small, so the concentration of the prepared solution is too low, so A does not meet the requirements;

B. The balance is a more precise measuring tool. When the weight is rusty, the mass of the weight is larger than the marked value, and n is larger, the concentration of the solution is higher, so B is consistent;

C ． When shaking to a constant volume, the liquid level drops and water is added, resulting in a larger volume of the solution and a lower concentration of the solution, so C is not met;

D. Looking down to read the scale when setting the volume causes the volume of the solution to be prepared to be too small and the concentration of the solution to be prepared to be too high, so D is met;

So the answer is: no glass rod is used for drainage; no 250ml volumetric flask is used; BD;