Afood item that is left out of the refrigerator turns brown and forms bubbles and gas. what are the signs that this is a chemical reaction? check all that apply.

a: heat is produced.

b: heat is absorbed.

c: bubbles appear.

d: a precipitate forms.

e: the color changes.

The answers would be:

C. Bubbles appear

E. The color changes

If you'd like to know more, you can read on:

Although your selections are indications of chemical reactions, if you are referring to only the chemical reaction that occurred in your example, then the two answers are the only choices.

A chemical reaction occurs when the reactants form a new product. Signs of a chemical reaction include change is smell, color and temperature. In some cases, precipitate forms.

C: Bubbles appear E: The color changes.

Explanation:

A chemical reaction is defined as the reaction in which a change in chemical composition takes place. A new substance is formed in these reactions.

Example: Oxidation of iron to ferric oxide is a chemical change.

Here iron which is grey in color changes first to green and then turns brownish red.

Characteristics of a chemical reaction:

1. change in color

2. heat is gained or lost

3. evolution of gas

4. formation of precipitate

Thus when a food item that is left out of the refrigerator changes colour  and evolution of gas takes place and thus would be a chemical change.

conservation of mass

mass before something happens = mass afterwards

prndulum needs thread, weight clock to time swings