Which of these factors make hydrogen fuel cells a better option than burning fossil fuels? hydrogen fuel cells have a higher energy efficiency. hydrogen fuel cells create less pollution. burning fossil fuels relies on outdated devices and technology. pure hydrogen is more readily available than fossil fuels. hydrogen fuel cells are more expensive than fossil fuels.

Order the following from smallest to largest atom, electron, quark, proton, neutron, molecule, nucleus

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas. in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

Which of the following happens during cell division? (a) energy is created (b) waste is eliminated (c) carbon dioxide is released (d) damaged cells are replaced