Explain why heat is often used in a laboratory experiment. a. To warm up the laboratory, b. To speed up a reaction

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

7. in the cycle, a virus integrates its dna into the host's dna, and its dna is replicated when the host dna is replicated. a. infectious b. retroviral c. lysogenic d.lytic

What is the pressure of 0.500 moles of carbon dioxide gas in a 2.5 l tank and at a temperature of 301 k? (r=0.0821 l·atm/mol·k) 3.08 atm 1.2 atm 0.23 atm 4.01 atm 4.94 atm