Physical v Chemical (Easy)

What is a physical change?

• A change that forms a new substance

• A change in shape or state with no new substance

• A change that burns material

• A color change that cannot be reversed

Answer explanation

A physical change involves a change in shape or state, such as melting or freezing, without creating a new substance. This distinguishes it from chemical changes, which do form new substances.

Which is an example of a chemical change?

• Water freezing

• Paper being cut

• Wood burning

• Ice melting

Answer explanation

Wood burning is a chemical change because it transforms the wood into ash and gases through combustion, altering its chemical structure. In contrast, freezing, cutting, and melting are physical changes.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What must happen for a chemical change to occur?

• A new shape forms

• A new substance forms

• Temperature drops

• A solid melts

Answer explanation

For a chemical change to occur, a new substance must form. This distinguishes chemical changes from physical changes, where the substance remains the same despite changes in shape or state.

Tags

NGSS.MS-PS1-2

Which is a sign of a chemical change?

• Folding a piece of paper

• Dissolving sugar in tea

• Gas bubbles forming in a reaction

• Crushing a rock

Answer explanation

Gas bubbles forming in a reaction indicate a chemical change, as it shows a new substance is being produced. The other options involve physical changes, where the substance's chemical identity remains the same.

Tags

NGSS.MS-PS1-2

Which change is only physical?

• Baking a cake

• Rusting iron

• Melting butter

• Fireworks exploding

Answer explanation

Melting butter is a physical change because it only alters the state of the butter from solid to liquid without changing its chemical composition. In contrast, baking a cake, rusting iron, and fireworks exploding involve chemical changes.

What happens in a chemical change?

• A substance keeps its identity

• Atoms rearrange to form something new

• No change in temperature

• Matter disappears

Answer explanation

In a chemical change, atoms rearrange to form new substances, altering their identity. This distinguishes chemical changes from physical changes, where the substance retains its identity.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What is not a sign of a chemical change?

• Color change

• Temperature change

• Formation of gas

• Breaking into smaller pieces

Answer explanation

Breaking into smaller pieces is a physical change, not a chemical one. In contrast, color change, temperature change, and gas formation indicate a chemical change due to new substances being formed.

Tags

NGSS.MS-PS1-2

Which is a chemical property of matter?

• Shape

• Melting point

• Ability to rust

• Size

Answer explanation

The ability to rust is a chemical property because it involves a change in the substance's chemical composition. In contrast, shape, melting point, and size are physical properties.

Which change in water is physical?

• Boiling

• Decomposition

• Reacting with sodium

• Electrolysis

Answer explanation

Boiling is a physical change because it involves a change in the state of water from liquid to gas without altering its chemical composition. The other options involve chemical changes.

Tags

NGSS.MS-PS1-4

Which of the following is most likely a chemical change?

• Ice melting

• Paper folding

• A nail rusting

• Chocolate softening

Answer explanation

A nail rusting is a chemical change because it involves a reaction with oxygen and moisture, resulting in the formation of iron oxide. In contrast, ice melting, paper folding, and chocolate softening are physical changes.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5