Determine the weight percent (wt%) of selenium in the soil sample and find the absolute uncertainty in the weight percent of selenium. Report the weight percent and absolute uncertainty with three significant figures.

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

Use this information to determine the number of calends electrons in the atoms. which of the following correctly compares the stability of the two atoms? a) both are unreactive b) both are highly reactive c) a is unreactive and d is reactive d) a is reactive and d is unreactive

Which of these is not an example of chemical weathering? a. iron-rich mineral rusting b. feldspar turning into clay c. limestone reacting with acid d. granite breaking up into sand