Which statement describes a chemical change? (1) alcohol evaporates.(2) water vapor forms snowflakes.(3) table salt (nacl) is crushed into powder.(4) glucose ( c6h12o6) and oxygen produce co2 and h20.

Calcium hydride (cah2) reacts with water to form hydrogen gas: cah2(s) + 2h2o(l) → ca(oh)2(aq) + 2h2(g) how many grams of cah2 are needed to generate 45.0 l of h2 gas at a pressure of 0.995 atm and a temperature of 32 °c?

Which is an example of the practical pursuit of alchemy? a. forming perfect substances. b. transforming base metals. c. developing metalworking techniques. d. linking spiritual characteristics with material substances.

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of