A car hoist is filled with oil. Why would it be difficult to use if it were full of air?

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.