Physical and Chemical Changes in Matter

Which process describes only a physical change?

• Fungus decomposing organic matter

• Leaves using carbon dioxide to make surgar

• Plants using nitrogen to make protein

• Water evaporating from salt water

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112.27.b.6.C

Researchers are investigating processes that happen during digestion.

Which answer choice describes only a physical change during digestion?

• Hydrochloric acid in the stomach breaks down proteins

• Chewing in the mouth breaks food into small pieces

• Enzymes in saliva start the digestion of starches before food is swallowed

• Bacteria in the intestines convert dietary fiber into fats

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112.27.b.6.C

Both the esophagus and the small intestine are involved in the digestion of food. The esophagus squeezes food into the stomach by wave-like muscle contractions. Peptidase enzymes in the small intestine break food molecules into smaller molecules.

Which statement best describes changes to food during digestion?

• The muscle contractions result in physical changes, while the action of the peptidase results in chemical changes

• The muscle contractions and the action of the peptidase both result only in physical changes

• The muscle contraction result in chemical changes, while the action of the peptidase results in physical changes

• The muscle contractions and the action of the peptidase both result only in chemical changes

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112.27.b.6.C

A student listed how different parts of the body work to aid in the digestion of food.

Which of the following is a chemical change that occurs to the food?

• The reduction in size of food particles as food is chewed

• The movement of food to the stomach after food is swallowed

• The breakdown of molecules of food by enzymes and acid in the stomach

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112.27.b.6.C

Many processes occur in the digestive system.

Which process is best classified as a physical change?

• Saliva converting the starch molecules in crackers into simple sugars

• Digestive enzymes breaking down proteins into smaller fragments

• Bacteria converting lactose into simple sugars in the intestines

• Teeth grinding an almond into smaller pieces in the mouth

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112.27.b.6.C

Which of the following does NOT indicate a chemical reaction is occurring? Check all that apply.

• Unknown A dissolves into Unknown B

• Unknown A creates fizzing and bubbles when combined with Unknown B

• Unknown A sinks to the bottom when added to Unknown B

• Unknown A floats to the top when added to Unknown B

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112.27.b.6.C

What evidence can you use to infer that a chemical reaction has occurred here?

• A dark solid formed on the zinc metal

• The zinc metal remained silver-colored and shiny

• None of these

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112.27.b.6.C

A chemical change

• changes matter from one form to another.

•  destroys matter.

• creates matter

• does not change matter in any way.

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112.27.b.6.C

Is wood burning a physical or chemical change?

• Physical 
• Chemical

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112.27.b.6.C

Which scientific observation, shown in the chart, indicates that a chemical reaction has NOT occurred?

• Number 1

• Number 2

• Number 3

• Number 4

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112.27.b.6.C