Chemical Reactions

What is the smallest part of an element that can exist as that element?

• atom

• element

• compound

• mixture

Answer explanation

The smallest part of an element that can exist as that element is an atom. Atoms are the basic building blocks of matter and retain the properties of the element.

What does subscript represent?

• The number of atoms in an element

• The number of compounds

• The number of molecules in a compound

• The total number of atoms in a compound

Answer explanation

The subscript represents the number of atoms in an element, not compounds, molecules, or the total number of atoms in a compound.

signs of a chemical change

• bubbles, energy change, odor change, color change, formation of a solid.

• a process in which one or more substances are changed into others

• A reaction that ABSORBS energy in the form of heat. Feels cold

• a chemical reaction in which heat is released to the surroundings. Feels hot.

Answer explanation

The signs of a chemical change include bubbles, energy change, odor change, color change, and the formation of a solid. These indicate a process where substances are transformed into others.

Law of Conservation of Mass

• Matter is not created nor destroyed in any chemical or physical change

• bubbles, energy change, odor change, color change, formation of a solid.

• The elements or compounds produced by a chemical reaction.

• A change in matter that produces one or more new substances

Answer explanation

The correct choice highlights the Law of Conservation of Mass, stating that matter is not created nor destroyed in any chemical or physical change.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

physical change

• A change in a substance that does not involve a change in the identity of the substance

• A reaction that ABSORBS energy in the form of heat. Feels cold

• Matter is not created nor destroyed in any chemical or physical change

• A solid that forms from a solution during a chemical reaction.

Answer explanation

A physical change is a change in a substance that does not involve a change in the identity of the substance, making it the correct choice.

Tags

NGSS.MS-PS1-4

Melting ice is a chemical reaction.

• false

• true

• don't pick

• don't pick

Answer explanation

Melting ice is a physical change, not a chemical reaction, as it does not involve a change in chemical composition.

Tags

NGSS.MS-PS1-4

A change in the state of matter is a sign of a ____ change.

• physical

• chemical

• .

• v

Answer explanation

A change in the state of matter is a sign of a physical change because it involves a transition between solid, liquid, or gas forms without altering the chemical composition.

Tags

NGSS.MS-PS1-4

Producing bubbles can be a sign of a _____ change.

• chemical

• physical

• .

• .

Answer explanation

Producing bubbles is often a sign of a chemical change due to the release of gases or formation of new substances through chemical reactions.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following would NOT indicate a chemical reaction has occured?

• ice melts

• gas formation

• solid formation

• color change

Answer explanation

The correct choice is ice melts because it is a physical change, not a chemical reaction. The other options involve chemical reactions.

Tags

NGSS.MS-PS1-2

The Law of Conservation of Matter (Mass) states that-

• Matter and energy are neither created nor destroyed; they merely change from one form to another

• Matter and energy are not created but can be destroyed

• Matter and energy are created and destroyed; they also change from one form to another.

• Matter and energy are created

Answer explanation

The Law of Conservation of Matter (Mass) states that matter and energy are neither created nor destroyed; they merely change from one form to another.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5