At constant pressure, which of these systems do work on the surroundings? check all that apply.

1. 2a(g) + 2b(g) > 5c(g)
2. a(g) + 2b(g) > 2c(g)
3. 2a(g) + b(s) > 3c(g)
4. 2a(g) + 2b(g) > 3c(g)

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line

Calculate the percent composition by mass of each element in al(oh)3. use at least three significant figures.

Harry lives in a city, and he has a lung condition known as asthma. on certain days, harry has to stay inside because pollutants in the air make it difficult for him to breathe. which of these pollution sources are nonpoint sources that might bother harry if he goes outside? choose the two that apply.