I) Interpret the chemical equation in terms of quantitative aspect. C3H8(g) + 5O2(g)->3CO2(g) + 4H2O(1/ce)

ii) Then, interpret it in terms of qualitative aspect. ​

Quantitative aspect: one mole of propane reacts with five moles of oxygen ( combustion ) to produce three moles of carbon dioxide and four moles of water.

Qualitative aspect: A colourless gas ( propane ) burns with a blue flame ( combination ) to form a colourless gas that turns lime water milky and drops of colourless liquid that turn anhydrous copper (ii) oxide from blue to white.

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