The atmosphere is:

a. the layer of water on earths surface

b. the layer of molten lave just below the earths crust

c. the layer of air surrounding earth’s surface

d. the layer of soil lying just over earth’s crust

Which of these properties, used alone, would be least useful in identifying most minerals? a. color b. luster c. streak d. density

What forms when chemical reactions combine pollution with sunlight?

Given the following at 25c calculate delta hf for hcn (g) at 25c. 2nh3 (g) +3o2 (g) + 2ch4 (g) > 2hcn (g) + 6h2o (g) delta h rxn= -870.8 kj. delta hf=-80.3 kj/mol for nh3 (g), -74.6 kj/mol for ch4, and -241.8 kj/mol for h2o (g)