What substance is a combination of different atoms

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.

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