Chemical Reactions Review

All atoms at the start of a chemical reaction are present at the end of the reaction.

• True

• False

All molecules in a substance remain intact during a chemical reaction

• True

• False

The substances at the start of a chemical reaction gather more atoms to make up for those lost in the reaction

• True

• False

Select all that are TRUE about this chemical reaction: Frying an egg

• chemical change

• physical change

• endothermic reaction

• exothermic reaction

Number of atoms in a chemical formula are defined by __________.

• compounds

• coefficients

• subscripts

• letters

Reactants can be described as all of the following except for

• present after chemical reaction

• ingredients

• the substances you start with

• Present before chemical reaction

Select which of the following apply to ice melting

• physical change

• chemical change

• endothermic reaction

• exothermic reaction

A bonfire gives off heat. This is an example of a(n) ____________ reaction.

• endothermic

• exothermic

In a chemical equation, the number of molecules in a chemical formula are defined by __________.

• subscipts

• coefficients

• compounds

• letters

A chemical compound can be defined as

• a combination of 2 or more elements

• the reactants in a reaction

• the products in a reaction

• 2 or more atoms in a formula