Một tia laser được phát ra từ nguyên tử nitơ có bước sóng 337 nm và có tổng năng lượng là 3,87 mJ. A) Tia laser trên thuộc vùng quang phổ nào của dãy quang phổ điện từ?

B)Tia laser đó chứa bao nhiêu photon?

Biết: vận tốc ánh sáng C = 3,0.108 (ms-1); hằng số Planck h = 6,626.10-34 (Js).

Which solution is an example of a nonelectrolyte? a. iodine in hexane b. sodium nitrate in waterc. acetic acid in waterd. hydrogen chloride in water

Salicylic acid is a very important acid. it is used to synthesize the aspirin by treating with acetic anhydride. a 0.2015-g sample of salicylic acid was dissolved in a 100.00-ml volumetric flask, and the solution was diluted to the mark. a 10-ml aliquot of this solution was titrated with standard naoh (0.01130 + 0.2% n) to a phenolphthalein faint pink color end point at 19.81 ml. (a) (calculate the normality of the salicylic acid solution used in the titration. (b) assuming the salicylic acid is pure, what is the equivalent weight of the salicylic acid? practice problems for the final exam (continued) (c) (calculate the inherent error in the determination of the equivalent weight you calculated in part (b). use the following absolute errors in the equipment /glassware when calculating the inherent error. 5.00-ml pipet: + 0.02 ml 100-ml volumetric flask: + 0.08 ml analytical balance: + 0.2 mg 25-ml buret: + 0.03 ml

What causes most sediment to wash or fall into a river