7th Grade Science - Introduction To Matter Final

An element is made of only one type of (a)   .

• Molecule

• Compound

• Atom

• Mixture

Answer explanation

An element consists of only one type of atom. Molecules and compounds are made of two or more atoms, while mixtures contain different substances. Therefore, the correct answer is atom.

Atoms can combine in different ways to form compounds.

• False

• True

Answer explanation

True is correct because atoms can bond in various ways, forming different compounds through chemical reactions, which is fundamental to chemistry.

Tags

NGSS.MS-PS1-1

Which best describes a molecule?

• A single atom

• A phase of matter

• Two or more atoms bonded together

• A type of mixture

Answer explanation

A molecule is defined as two or more atoms bonded together, forming a distinct chemical entity. This distinguishes it from a single atom, a phase of matter, or a type of mixture.

Tags

NGSS.MS-PS1-1

Which is a substance, not a mixture?

• Air

• Trail mix

• Pure water

• Salad

Answer explanation

Pure water is a substance made of only H2O molecules, while air, trail mix, and salad are mixtures of different components. Therefore, pure water is the correct answer as it is not a mixture.

Mass is measured in (a)   .

• Liters

• Seconds

• Grams

• Meters

Answer explanation

Mass is a measure of the amount of matter in an object, which is quantified in grams. Liters measure volume, seconds measure time, and meters measure length, making grams the correct unit for mass.

Volume is the amount of (a)   an object takes up.

• Mass

• Weight

• Space

• Energy

Answer explanation

Volume refers to the amount of space an object occupies. It is not related to mass, weight, or energy, making 'space' the correct choice to fill in the blank.

Weight depends on gravity, but mass does not.

• False

• True

Answer explanation

The statement is true because weight is the force exerted by gravity on an object, which varies with location, while mass is a measure of the amount of matter in an object and remains constant regardless of gravity.

Tags

NGSS.MS-PS2-4

Density is calculated using (a)   .

• Temperature

• Shape

• Mass and volume

• Weight only

Answer explanation

Density is defined as mass per unit volume. Therefore, the correct way to calculate density is by using mass and volume, making 'Mass and volume' the right choice among the options provided.

Which has more density?

• Styrofoam

• Balloon

• Steel

• Feather

Answer explanation

Steel has a much higher density than Styrofoam, balloons, and feathers. Density is mass per unit volume, and steel is a dense metal, while the others are lightweight materials.

A physical change does NOT make (a)   .

• A phase change

• A shape change

• A new substance

• A size change

Answer explanation

A physical change alters the form or appearance of a substance without changing its chemical composition. Therefore, it does not create a new substance, which is characteristic of a chemical change.