Is it a physical or chemical change when a candle is lit

The covalent compound acetylene, which is the fuel of the oxyacetylene torch used by welders, has the molecular formula c2h2. the covalent compound benzene, a commercial solvent, has the molecular formula c6h6 each of these covalent compounds contains carbon and hydrogen atoms in a one-to-one ratio. would it be correct to write the chemical formulas of each as ch? explain.

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.

What is the subscript for oxygen in its molecular formula