In the classroom during a visual inspection of a rock, a student recorded four statements about the rock. which statement about the rock is an observation?

1)the rock formed deep in the earth's interior
2)the rock cooled rapidly
3)the rock dates from the precambrian era
4)the rock is black and shiny

Which describes interactions between substances and stomata during photosynthesis? check all that apply. oxygen enters stomata. oxygen is released through stomata. carbon dioxide enters stomata. carbon dioxide is released through stomata. hydrogen enters stomata. hydrogen is released through stomata.

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)