Chemical reactions

Which remains the same during a chemical reaction?

• the temperature of the elements

• the total number of atoms

• the total number of compounds

Which of the following describes a chemical change?

• A metal fork was melted.

• A metal fork became bent.

• A metal fork was cut in half.

• A metal fork became rusted.

Element A and element B chemically combine to form substance C. Substance C must be

• a solution

• a compound

• an element

• a mixture

All chemical reactions have a conservation of

• mass, only

• mass and charge, only

• charge and energy, only

• mass, charge, and energy

Which is an example of a chemical reaction?

• nails rusting

• glass melting

• sugar dissolving

• alcohol vaporizing

A banana turning brown is a chemical change.

• True

• False

The substances at the start of a chemical reaction that change to other substances are known as

• products

• reactants

Which of the following is the best evidence for a chemical reaction?

• gas bubbles

• formation of a new substance

• change in state

• change in temperature

Iron + Oxygen --> Iron Oxide (rust)

The product (s) in the following reaction is/are

• Iron

• Oxygen

• Iron Oxide (rust)

Which statement is true of all chemical reactions?

• They can go in just one direction.

• They occur only in science labs.

• They create new elements.

• They break and reform bonds.