Understanding Changes in Matter

A student observes a piece of metal rusting over time. Which of the following best describes this process?

• Physical change

• Chemical change

• Both physical and chemical change

• Neither physical nor chemical change

Tags

TEKS.SCI.7.6C

Which of the following scenarios best illustrates a physical change?

• Burning a piece of paper

• Dissolving sugar in water

• Baking a cake

• Rusting of iron

Tags

TEKS.SCI.7.6C

A solution is made by dissolving 10 grams of salt in 100 mL of water. If the solution is diluted by adding 100 mL of water, what is the new concentration of the solution?

• 5 grams per 100 mL

• 10 grams per 200 mL

• 10 grams per 100 mL

• 20 grams per 200 mL

Tags

TEKS.SCI.7.6D

If you have a solution with a high concentration of solute, which of the following actions will decrease the concentration?

• Adding more solute

• Adding more solvent

• Heating the solution

• Stirring the solution

Tags

TEKS.SCI.7.6D

A student is investigating how temperature affects the rate of dissolution of sugar in water. Which of the following is a reasonable hypothesis for this investigation?

• Increasing the temperature will decrease the rate of dissolution.

• Increasing the temperature will increase the rate of dissolution.

• Temperature has no effect on the rate of dissolution.

• The rate of dissolution is highest at room temperature.

Tags

TEKS.SCI.7.6E

Which of the following methods would most effectively increase the rate at which a solid solute dissolves in a liquid solvent?

• Decreasing the surface area of the solute

• Decreasing the temperature of the solvent

• Stirring the solution

• Allowing the solution to sit undisturbed

Tags

TEKS.SCI.7.6E

A student is tasked with distinguishing between a physical and a chemical change. Which of the following observations would indicate a chemical change?

• A change in shape

• A change in color

• A change in state

• A change in size

Tags

TEKS.SCI.7.6C

When a solute is added to a solvent and the solution is stirred, which of the following best describes the effect on the rate of dissolution?

• Stirring decreases the rate of dissolution.

• Stirring has no effect on the rate of dissolution.

• Stirring increases the rate of dissolution.

• Stirring causes the solute to precipitate out.

Tags

TEKS.SCI.7.6E

A student dissolves 5 grams of a solute in 50 mL of water. If the student wants to double the concentration of the solution, what should they do?

• Add 5 more grams of solute

• Add 50 mL more of water

• Remove 25 mL of water

• Remove 5 grams of solute

Tags

TEKS.SCI.7.6D

Which of the following factors will not affect the rate of dissolution of a solid solute in a liquid solvent?

• Temperature of the solvent

• Surface area of the solute

• Volume of the solvent

• Agitation of the solution

Tags

TEKS.SCI.7.6E