1. The law of conservation of mass tells us, in part, that matter is neither created nor destroyed. How can we see this by using chemical reactions? A. By measuring the mass of the reactants and products in a closed system B. By writing a balanced chemical equation C. By counting the number of atoms on each side of the equation D. All of the above

Not all tiles will be usedidentify the element present in each star based on the gaps observed in wavelengths of its light refer to this table containing absorption wavelengths (in nm) of several different elements the table ishelium 447, 502 ,587 ,668carbon 427 ,515, 600 ,678sulfur 425, 565, 639, 675xenon 484, 590, 687calcium 429 ,527, 593, 645silver 421 ,521, 662

Classify the following soils according to the uscs classification system. provide appropriate uscs designations. a) this sample of well-graded gravel with sand was obtained from a large earthen dam in vancouver, canada. the sample has 73% fine to coarse sub-angular gravel, 25% fine to coarse sub-angular sand and 2% fines. the maximum size of the particles is 75 mm. the coefficient of curvature is 2.7, while the uniformity coefficient is 12.4. b) this dark brown and wet soil with a “strong organic odor” has 100% passing the no. 200 sieve. the liquid limit of the material is 32% when not dried and is 21% when oven-dried. the plastic index is 21% when not dried. c) this sand has 61% predominantly fine sand, 23% silty fines, and 16% fine sub-rounded gravel size. the maximum size is 20 mm. the liquid limit is 33% and the plastic limit is 27%. d) this soil has 74% fine to coarse sub-angular reddish sand and 26% organic and silty dark brown fines. the liquid limit is 37% when not dried and is 26% when oven dried. the plastic index is 6% when not dried.

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.