Is there any terminal identification mark for rheostat as positive, negative?

In a given chemical reaction, the energy of the products is greater than the energy of the reactants. which statement is true for this reaction?

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

Estimate the change in the gibbs energy and molar gibbs energy of 1.0dm3 of octane when the pressure acting on it is increased from 1.0 atm to 100 atm. the mass density of octane is 0.703 g cm−3