Let's put it all together!

Two chemical formulas are shown in the table below.

• Two elements

• One element and one compound

• Two compounds

• One element and one atom

Tags

NGSS.MS-PS1-1

Some students observe the physical properties of five different substances to determine if the substances are elements or compounds. Which samples represent a compound? Select TWO correct answers.

• Sample 1

• Sample 2

• Sample 3

• Sample 4

• Sample 5

Tags

NGSS.MS-PS1-1

Sodium sulfate (Na₂SO₄) is used to produce many products. Which elements are represented in the formula AND how many atoms of each element are represented in the formula? Read the question carefully. Then enter your answer in the box provided.

Tags

NGSS.MS-PS1-1

Serotonin is a chemical substance that helps relay messages in the human brain. The formula for one molecule of serotonin is shown below. How many atoms in all are in a molecule of serotonin? Enter your answer in the box.

Tags

NGSS.MS-PS1-1

Which statement describes an action that is MOST LIKELY a result of a chemical change?

• A pan of water was heated on a stove, and steam formed.

• A liquid was mixed with another liquid, and a precipitate formed.

• A liquid was sprayed into the air, and a sweet odor occurred.

• A child blew through a wand filled with soap, and bubbles were produced.

Tags

NGSS.MS-PS1-2

The picture below shows a beaker containing a clear liquid with a temperature of 20°C. A blue powder is added to the liquid. Which of the following provides the BEST evidence that a physical change occurred?

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Tags

NGSS.MS-PS1-4

A saltwater solution sits on a science lab table for one week, causing some of the solvent to evaporate. Which statement BEST describes how the concentration of the saltwater solution will change?

• The concentration will decrease.

• The concentration will first increase, then decrease.

• The concentration will remain the same.

• The concentration will increase.

Examine the diagram and answer these questions: - What is the solvent and solute in the solutions? - What can be added to dilute Sample A?

Students performed a lab investigation to determine how temperature, surface area, and agitation affect the rate at which a solid solute dissolves in an aqueous solution. The students poured 100 g of sugar into one liter of water. Which of the following models will the rate of sugar dissolution be the fastest?

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Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

A student adds one teaspoon of rock salt to a bottle of cold water and shakes the bottle. Which of the following BEST explains why shaking the water will affect the dissolving rate of the salt?

• A. Shaking the bottle of water exposes the rock salt to the solvent faster.

• B. Shaking the bottle of water causes the water to evaporate faster allowing the rock salt to dissolve.

• C. Shaking the bottle of water exposes the rock salt to the water, creating a precipitate.

• D. Shaking the bottle of water helps the water temperature stay cold allowing the rock salt to dissolve.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5