# 2nd Grade Science : Argue changes caused by heating/cooling can be reversed

## Example Questions

### Example Question #21 : Changes Caused By Heating And Cooling

An example of a change caused by heating or cooling that can be reversed would be the melting of a crayon and then freezing it back into a solid cube.

True

False

True

Explanation:

The statement above is a true statement and example of how heating and cooling can be reversed. If you melt a crayon, it goes from a solid to a liquid. This can be reversed, and the crayon can be returned to a solid-state by freezing or cooling it. Some changes cannot be reversed, but this example can be reversed.

### Example Question #22 : Changes Caused By Heating And Cooling

Becca says that some heating changes can be reversed. She gives the example of melting butter. She says that you can turn a solid piece of butter into a liquid and then turn it back to a solid. Her friend Melva disagrees and says butter cannot be changed back and forth.

Who is correct, and why?

There is not enough information to tell who is correct.

Becca; she is correct because the changes to butter can be reversed. Becca could melt the butter by applying heat and then put it back into the refrigerator to cool it down and make it solid again.

Neither; both of the girls are wrong

Melva; she is correct because butter cannot be changed. If the butter is turned into a liquid it cannot be reversed and turned back to a solid.

Becca; she is correct because the changes to butter can be reversed. Becca could melt the butter by applying heat and then put it back into the refrigerator to cool it down and make it solid again.

Explanation:

Butter is an excellent example of a heating change that can be reversed. Becca can melt butter and then cool it to reverse the effects. Melva disagreed with her but is unfortunately wrong in this case. Some heating and cooling changes can be reversed.

### Example Question #23 : Changes Caused By Heating And Cooling

Which material can be heated or cooled, and then have the changes reversed?

Ice cube

Egg

Cake

Ice cube

Explanation:

Some objects or materials can be heated or cooled, and the changes caused can be reversed. An ice cube could have the changes applied to it reversed. If you heat an ice cube it will melt, you can refreeze it to turn it back to a solid. If you toast bread, bake a cake, or cook an egg, that change cannot be reversed.

### Example Question #24 : Changes Caused By Heating And Cooling

Will says some changes caused by heating cannot be reversed. Angelo says some changes can be reversed.

Their father takes a popsicle out of the freezer and sets it on the counter. The popsicle begins to melt. He gets a call and puts it back into the freezer.

Using this example who is correct, Will or Angelo, and why?

There is not enough information to decide who is correct.

Neither of the boys is correct.

Angelo; He is correct because this is a change that can be reversed. If the popsicle were melting and put back into the freezer, it would refreeze and become solid again.

Will; He is correct because this is a change that cannot be reversed. Once the popsicle has started to melt, there is no changing that.

Angelo; He is correct because this is a change that can be reversed. If the popsicle were melting and put back into the freezer, it would refreeze and become solid again.

Explanation:

In the situation presented, Angelo is correct. The changes to the popsicle can be reversed. Once it has been heated up and starts to melt, there is a change. In this case, their father puts it back into the freezer when he gets the call; this would cause the popsicle to refreeze. In some instances, these changes can not be reversed, but in this example, it is possible.

### Example Question #25 : Changes Caused By Heating And Cooling

Which photo represents a heating or cooling change that can be reversed?

Explanation:

The photo that represents a heating or cooling change that can be reversed is the candle with melting wax. Once the candle is no longer lit, the wax will reharden and no longer will be a liquid. Baking a cake, heating toast, and lighting fireworks are all examples of applying heat in a way that cannot be reversed.

### Example Question #26 : Changes Caused By Heating And Cooling

An example of a change caused by heating or cooling that can be reversed would be the melting of a candy bar and then putting it into the refrigerator to reset the chocolate.

False

True

True

Explanation:

The statement above is a true statement and example of how heating and cooling can be reversed. If you melt a candy bar, the chocolate goes from a solid to a liquid. This can be reversed, and the candy bar can be returned to a solid-state by freezing or cooling it. Some changes cannot be reversed, but this example can be reversed.

### Example Question #27 : Changes Caused By Heating And Cooling

Which material can be heated or cooled, and then have the changes reversed?

Explanation:

Some objects or materials can be heated or cooled, and the changes caused can be reversed. Ice could have the changes applied to it reversed. If you heat ice, it will melt, you can refreeze it to turn it back to a solid. If you toast bread, bake a donut, or cook a marshmallow, that change cannot be reversed.

### Example Question #28 : Changes Caused By Heating And Cooling

Which photo represents a heating or cooling change that can be reversed?

Explanation:

The photo that represents a heating or cooling change that can be reversed is melting ice cream. The ice cream could be put back into the freezer, and it would no longer melt and would return to a solid.

### Example Question #29 : Changes Caused By Heating And Cooling

An example of a change caused by heating or cooling that can be reversed would be the baking of a birthday cake.

False

True

False

Explanation:

The statement above is a false statement and an example of how heating and cooling can NOT be reversed. If you bake a cake, a chemical change has occurred when the heat was applied. This cannot be reversed, and the cake cannot be returned to a batter or individual ingredients.

### Example Question #30 : Changes Caused By Heating And Cooling

This photo represents a change due to heating or cooling that can be reversed.