Unit 2 Assessment Review

Which of the following is NOT a physical characteristic?

• Color

• Density

• Flammability

• Boiling Point

Answer explanation

Flammability is a chemical property, indicating how a substance reacts with fire, while color, density, and boiling point are physical characteristics that describe the state and appearance of a substance.

As temperature increases, density:

• Increases

• Decreases

• Stays the same

• Cries in banana

Answer explanation

As temperature increases, substances typically expand, leading to a decrease in density. This is because density is mass per unit volume, and with increased volume at constant mass, density decreases.

Tags

NGSS.MS-PS1-4

If a ball has a mass of 10 grams and a volume of 5 mL, what is its density?

• 2 g/mL

• 5 g/cm3

• 50 g/mL

• 15 g/cm3

Answer explanation

Density is calculated as mass divided by volume. Here, density = 10 grams / 5 mL = 2 g/mL. Thus, the correct answer is 2 g/mL.

Heat (aka thermal energy):

• causes substances to decrease in volume

• is lower in objects that are hot

• comes from kinetic energy

• is higher in objects that move slowly

Answer explanation

Heat comes from kinetic energy, as it is the energy of motion at the molecular level. Hot objects have higher kinetic energy, leading to increased thermal energy, making this choice correct.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

What is absolute zero?

• the freezing point of water, where the molecules condense from a liquid to a solid

• the point of vaporization, where the molecules evaporate from a liquid to a gas

• 0 degrees C, or the temperature at which molecules no longer have kinetic energy

• 0 degrees K, or the temperature at which molecules no longer have kinetic energy

Answer explanation

Absolute zero is defined as 0 degrees K, the temperature at which molecular motion ceases and molecules have no kinetic energy. This is the correct choice, distinguishing it from other temperature points.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

To figure out how to make our egg suspend, we had to set the density of the water equal to:

• 1 g/mL

• the density of the egg

• the volume of the egg

• more than 1

Answer explanation

To suspend the egg in water, the water's density must equal the density of the egg. This balance allows the egg to neither sink nor float, achieving neutral buoyancy.

Molecules:

• diffuse faster in hot water than cold water

• diffuse faster in cold water than hot water

Answer explanation

Molecules diffuse faster in hot water than in cold water because higher temperatures provide more energy, increasing molecular movement and collision frequency, which enhances diffusion rates.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which state of matter has the least kinetic energy (with water being the exception)?

• Solid

• Liquid

• Gas

Answer explanation

Solids have the least kinetic energy among the states of matter because their particles are closely packed and vibrate in fixed positions, resulting in minimal movement. This is true except for water, which behaves differently.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

In order for a substance to float on water, it must have a density:

• greater than water

• less than water

• equal to water

• equal to that of a Turkish Hen

Answer explanation

For a substance to float on water, it must have a density less than that of water. If its density is greater, it will sink. Therefore, the correct answer is 'less than water'.

What is the density of pure water?

• 5 g/mL

• 1 g/mL

• -3 g/mL

• 100 g/cm^3

Answer explanation

The density of pure water is commonly accepted as 1 g/mL at 4°C. This means that 1 milliliter of water has a mass of 1 gram, making 1 g/mL the correct answer. Other options are incorrect.