What is the most fundamental characteristic that defines a chemical reaction?

The substances change their state of matter, such as from a liquid to a gas.

The temperature of the mixture increases or decreases significantly.

New substances with properties different from the original ones are formed.

The original substances are simply mixed together without changing their identity.

Which of the following describes a physical change, rather than providing evidence of a chemical reaction?

An iron nail rusting and turning reddish-brown.

An antacid tablet fizzing and producing bubbles in water.

A puddle of water evaporating on a hot day.

Two liquids being mixed to form a yellow solid.

the vinegar is dissolving the baking soda powder.

the two substances have different densities.

The mixture changed from clear to a deep blue color.

The mixture became slightly warmer after mixing.

A solid material formed and settled out of two mixed liquids.

Bubbles of gas were seen rising from the liquid.

The process was reversible by evaporating the water.

A solid was present at the beginning and the end.

The beaker did not get hot or cold during the process.