Science Unit 2 USA

David is making lemonade. He adds sugar to some lemon juice in water. The sugar starts to dissolve. What can David do to speed up the dissolving process?

• add ice cubes to the lemonade

• pour the lemonade in a pitcher

• stir the lemonade with a spoon

• put the lemonade in the refrigerator

Interactions between substances can produce chemical or physical changes. Which of the following describes a chemical change?

• painting a picture on the sidewalk

• shaking a soda can and opening the can

• toasting a piece of bread in a toaster oven

• stirring iced tea so that the sugar will dissolve

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student wants to remove the salt from a mixture of sand and salt in order to get only pure sand. He adds water to the mixture. Why is this step helpful?

• Salt dissolves in water.

• Sand dissolves in water.

• The water freezes to the salt.

• The salt floats on top of the water.

The ripening of an apple is an example of a chemical change. In order to investigate this process, Jennifer places one apple at room temperature and one in the refrigerator. After ten days Jennifer checks the ripeness of each apple. Which statement best explains the expected results?

• The apple at room temperature will ripen more slowly because higher temperatures increase the rate of chemical reactions.

• The apple at room temperature will ripen more slowly because higher temperatures decrease the rate of chemical reactions.

• The apple at room temperature will ripen more quickly because higher temperatures increase the rate of chemical reactions.

• The apple at room temperature will ripen more quickly because higher temperatures decrease the rate of chemical reactions.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which of these is a physical change that occurs because of a decrease in temperature?

• boiling

• condensation

• evaporation

• melting

Tags

NGSS.MS-PS1-4

Carl is cooking with his father. The recipe tells them to add butter, oil, salt, and noodles to a pot of boiling water and stir until dissolved. Which of the four ingredients is the only one that will dissolve?

• butter

• noodles

• oil

• salt

Breanna is investigating the changes in various substances as they are heated. She places four unknown solids into individual test tubes and heats them in a water bath. She records her observations after 0, 10, and 20 minutes in the water bath. If a substance has melted, she measures its temperature.

What can Breanna conclude from her data?

• heating these solids did not change their state of matter

• as solids are heated, some will rapidly increase in temperature and melt

• even if their temperatures increase much higher, substances 1 and 3 will not melt

• when different solids are heated in the same way, their temperatures change in the same way

Tags

NGSS.MS-PS1-4

NGSS.MS-PS1-2

A student adds 5 grams (g) of sugar to a cup of water at 25 degrees Celsius (ºC). Which result will most likely happen if the temperature of the water is increased to 50°C?

• The sugar will not dissolve.

• The sugar will dissolve faster.

• The sugar will dissolve slower.

• The sugar will dissolve at the same rate.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Sharpening a pencil and tearing paper are examples of physical changes. Which statement best describes why these are physical changes and not chemical changes?

• There is a change in how the objects are used.

• There is a change in appearance of the objects.

• There is a change in the materials from which the objects are made.

• There is a change in the appearance of the objects and the materials from which they are made.

Which of the following objects has a mass that would be closest to a balloon filled with air?

• a golf ball

• a patio brick

• a dry sponge

• a science textbook