Which of the following describes an endothermic reaction? a. wood burns in a campfire. b. the shell of an egg breaks when dropped. c. a balloon stretches as air is blown into it. d. batter becomes a pancake when heated.

Inside a flashbulb, oxygen surrounds a thin coil of magnesium. when the flashbulb is set off, a chemical reaction takes place in which magnesium combines with oxygen to form magnesium oxide. which of the chemical equations matches the reaction above? a. mg + o2 mgo2 + energy b. 2mg + o mg2o + energy c. 2mg + o2 2mgo + energy d. mg + o mgo + energy