when a candle burns both physical and chemical changes take place at identify these changes give another example of a familiar process in which both the chemical and physical changes takes place.

So, the melting of wax and vapourisation of melted wax are physical changes. Chemical Changes : The wax near flame burns and gives new substances like carbon dioxide, carbon soot, water vapour, heat and light. LPG is another example of a familiar process in which both the chemical and physical changes take place.

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