Evidence of Chemical changes

1. The Best Friend's Club uses "invisible ink" to write notes to each other. The invisible ink is actually lemon juice that is clear when it dries on paper, but turns brown when a club member holds a burning candle under the paper. Once it is heated, it is never invisible again.

What type of change is occurring when the paper is heated?

• Chemical Change

• Physical Change

• Elemental Change

• Temperature Change

Tags

NGSS.MS-PS1-2

A student mixes two clear liquids together. After a few minutes, a white powdery solid can be seen settling on the bottom of the test tube. Which of the following is a conclusion that the student can draw based on these observations? The two clear liquids-

• were pure substances before they were mixed

• are toxic and should be handled with extreme caution

• have gone through a chemical change in which a new substance called a precipitate was produced

• have been stored too long and are no longer good

Tags

NGSS.MS-PS1-2

Shredding paper is an example of a

• chemical change

• physical change

• physical property

• chemical property

A student added white crystals to a clear liquid. The crystals dissolved in the liquid. After a few seconds, the liquid became quite warm and then turned bright red in color. Indications that a chemical change was taking place could be observed when –

• the white crystals were added to the clear liquid.

• the crystals dissolved in the liquid leaving only the liquid visible

• There are no indications of chemical change

• the temperature of the liquid increased and an unexpected color change occurred.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

A student observes some sugar as it is heated and burns. The student concludes that a chemical reaction has occurred. Which of the following observations about the burning sugar provides evidence of a chemical reaction?

• Heat is added to the sugar crystals.

• The sugar melts and becomes a liquid.

• Gas is produced as the sugar turns black.

• No evidence of chemical reaction is present.

Tags

NGSS.MS-PS1-2

Olivia had a beaker with a small amount of baking soda. She added a few drops of vinegar to the baking soda and observed fizzing and bubbling. Based on her observation, which of these can Vanessa determine about the new substance formed by mixing the baking soda and vinegar?

• It was hot.

• It was a gas.

• It was magnetic.

• It was a conductor

Tags

NGSS.MS-PS1-2

When two liquids are mixed and a solid forms as a result of a reaction, the solid is called a

• participant

• percipitate

• polypeptide

• precipitate

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The brown color of a cut apple can be called

• physical change

• chemical change

• evidence of chemical reaction

• all of the above

Tags

NGSS.MS-PS1-2

Which of the following examples shows that a chemical reaction has occurred? 

• A rock breaks into smaller pieces when it is struck with a hammer.
• Rust forms on a hammer that has been left outside to long. 
• A cup of water turns pink when a few drops of red food coloring are added. 
• A solid is formed when heat is removed from a sample of water. 

Tags

NGSS.MS-PS1-2

Evidence of a chemical reactions is anything that shows - 

• a new substance has formed
• a solid dissolved in a liquid
• interaction between 2 gases
• a change in the state of matter

Tags

NGSS.MS-PS1-2