fire is a kind of chemical reaction & fire causes burning ->  burning something with fire is a kind of chemical reaction  burning something with fire is a kind of chemical reaction & a lit candle is a source of fire ->  burning something with a lit candle is a kind of chemical reaction  burning something with a lit candle is a kind of chemical reaction & magnesium is a kind of substance ->  burning magnesium with a lit candle is a kind of chemical reaction  burning magnesium with a lit candle is a kind of chemical reaction & chemical reactions cause chemical change -> burning magnesium with a lit candle will lead to a chemical change