1 Fe3O4 + 4 H2 → 3 Fe + 4 H2O Calculate the number of grams of Fe3O4 that are required to react completely with 3.75 x 1024 molecules of H2.

explanation:

crosscutting concepts have application across all domains of science. as such, they are a way of linking the different domains of science. they include patterns; cause and effect; scale, proportion, and quantity; systems and system models; energy and matter; structure and function; and stability and change.

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them  

d) a person who learns about the world by observing it.

explanation:

scientist are people who discover why and how things are done and made in the world.