Afirework exploding would be an example of a(n) question 23 options: exothermic reaction endothermic reaction physical change formation of a precipitate

Answer is: Exothermic reaction.

Exploding fireworks is chemical change (chemical reaction), because new substances are formed, the atoms are rearranged and the reaction is followed by an energy change (energy is released).

There are two types of reaction: endothermic reaction (chemical reaction that absorbs more energy than it releases) and exothermic reaction (chemical reaction that releases more energy than it absorbs).

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.