Have you ever looked closely at the flame? Which part of ... In this activity you will light some candles to find out—no special occasion required! Background Whether they are on a birthday ...

Be sure no liquid comes out – just the gas. Carbon dioxide molecules are heavier than air. Because of this, they push the oxygen and other molecules in the air out of the way as they sink down over ...

asks a reader. Think of the flame on a candle as a helium-filled balloon: No matter which way you hold the string or the tied-off end, the balloon will stubbornly right itself. It's as if candle ...