Chemical and Physical Changes

Leo keeps a bowl of water in the freezer for a few hours to obtain substance X. He then leaves a second bowl of water on the table for an hour to obtain substance Y.Which statement correctly describes substances X and Y?

• X and Y both are solids.

• X and Y both are liquids.

• X is a liquid, and Y is a solid.

• X is a solid, and Y is a liquid.

Tags

NGSS.MS-PS1-4

Margaret places a cube of butter in a pan and places the pan on a heated stove top. What change can she observe?

• a change of state and a change in shape a change of state and a change in shape

• a change in mass alone

• a change of state alone

• a change of color alone

Tags

NGSS.MS-PS1-4

A student listed some changes observed in daily life. Which change is an example of a physical change?

• forming yogurt from milk

• rotting of a dead log of wood

• heating of corn kernels to make popcorn heating of corn kernels to make popcorn

• crushing sugar candy into powder

Which activity is an example of a physical change?

• An ice cube melts into liquid water when heated.

• A piece of wood produces heat when it is burned.

• A metal chain rusts when left outside

• An apple turns brown when it is exposed to air.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

A boy holds an ice cream bar outside in the hot Sun, causing it to begin to melt. The boy quickly puts the entire melted ice cream bar in a paper cup and places it in the freezer to refreeze.Which statement describes the weight of the ice cream bar?

• The ice cream bar weighed more before it melted.

• The ice cream bar weighed the same after it was refrozen.

• The ice cream bar weighed more after it was refrozen.

• The ice cream bar weighed less before it melted.

Tags

NGSS.MS-PS1-5

Caroline left an ice cube on the kitchen counter. An hour later, she notices that the ice has changed.What evidence would Caroline have observed that shows a physical change has occurred?

• The ice melted to form a liquid.

• The ice is now colder.

• The ice melted to form a solid.

• The ice is now clear.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

A student fills a beaker with 100 mL of water, adds 10 g of salt, and stirs the components until the salt is completely dissolved, making a salt solution. The student then places the beaker on a hot plate, evaporates the water, and observes that salt is left in the beaker.Based on the student’s observation, which statement is true about solutions?

• The components of solutions keep their properties when mixed.

• The formation of solutions changes the physical properties of water.

• Solutions formed with water are always separated by filtration.

• When components are mixed to form solutions, new substances are formed.

Tags

NGSS.MS-PS1-4

A student places a 200 g chocolate bar in a pan, heats the pan, and observes that the bar melts. The student removes the pan from the heat and leaves the chocolate undisturbed to cool. After an hour, the student observes that the chocolate has become a hard solid with a mass of 200 g. How can the student classify this change?

• It is an irreversible change because the shape of the chocolate changes.

• It is a reversible change because the mass of the chocolate is the same after cooling.

• It is a reversible change because the chocolate returns to its solid state after cooling.

• It is an irreversible change because the solid chocolate changes into a liquid.

Tags

NGSS.MS-PS1-4

Which action causes a physical change?

• Cutting a piece of paper in half.

• Burning a wood log.

• Baking a cake

• Rusting metal

Megan lights a candle and watches it burn. She observes that some wax melts, some smoke comes from the wick, the wick burns, and then the melted wax hardens again.Which represent chemical changes?

• The wick burns, and smoke comes from the wick.

• Some wax melts, and smoke comes from the wick.

• Some wax melts, and later melted wax hardens again.

• Smoke comes from the wick, and later melted wax hardens again.

Tags

NGSS.MS-PS1-2