Chemical Properties Answers

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Jenna took an open bowl of leftover mashed potatoes from the refrigerator and noticed a difference in smell. She determined that chemical changes occurred since the potatoes were first placed there.

A
a change of odor
B
a decrease in temperature
C
a change in moisture content
D
a decrease in mass
2
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A scientist is examining an unknown solid. Which procedure would most likely help determine a chemical property of the substance?

A
heating it to find the temperature at which it melts
B
exposing it to a flame to see if it catches on fire
C
hitting it with a hammer to determine if it breaks or bends
D
placing it in water to find out whether or not it dissolves
3

Justin is making a snack. He toasts a piece of bread and spreads peanut butter and jelly on it. Then he cuts an apple into several slices and adds these to his plate. Next, Justin mixes a scoop of lemonade powder into a glass of water, mixes it, and adds ice.

A
one
B
two
C
three
D
four
4

In a science demonstration, a teacher mixed zinc (Zn) with hydrogen chloride (HCl) in a flask and quickly attached a balloon over the mouth of the flask. Bubbles formed in the solution and the balloon inflated.

A
The Zn and HCl both retained their identity.
B
Either Zn or HCl, but not both, retained its identity.
C
Evaporation of one of the substances occurred.
D
One or more new substances formed.
5

Which statement describes all chemical changes, but not all physical changes?

A
Bubbles are produced.
B
A new substance forms.
C
Phase changes occur.
D
A color change occurs.
6

Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he placed the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation.

A
He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred.
B
He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.
C
He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.
D
He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.
7

Investigations were carried out in a science lab to explore the topic of chemical and physical changes.Investigation AStep 1. Add 5 tsp. salt to 100 ml warm water and stir until most or all of the salt is no longer visible.Step 2. Heat the salt solution on a burner until only a white solid remains.Investigation BStep 1. Mix 10 tsp. white sugar into 100 ml water and stir until most or all of the sugar is no longer visible.Step 2. Heat the sugar solution on a burner until the solution thickens and turns brown.

A
Investigation A, Step 1 and Investigation B, Step 1
B
Investigation A, Step 2 and Investigation B, Step 2
C
Investigation A, Step 2 only
D
Investigation B, Step 2 only
8

Which characteristic of a substance is considered a chemical property?

A
its boiling point
B
its reactivity
C
its density
D
its conductivity
9

Which statement best describes a physical change?

A
Changes can occur to certain chemical properties of the substance, but the overall shape of the substance will remain the same.
B
Changes can occur to certain physical properties of the substance, but the overall shape of the substance will remain the same.
C
Changes can occur to physical properties of a substance, but the chemical composition of the substance remains the same.
D
Changes can occur to chemical properties of a substance, but the chemical composition of the substance remains the same.
10

Which best explains why making a pancake from batter is an example of a chemical change?

A
The pancake that forms is a different state of matter.
B
The change from batter to pancake can be reversed.
C
A new substance forms when the batter is cooked.
D
The batter changes shape when it is cooked.

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