Chemical Properties Answers

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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.
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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
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

Which laboratory activity involves a chemical change?

A
leaving a copper penny in vinegar until it turns green
B
boiling saltwater for several minutes until only solid salt remains
C
extracting iron filings from a sand mixture using a magnet
D
crushing a rock with a hammer to extract mineral deposits
5

Which characteristic of a substance is considered a chemical property?

A
its boiling point
B
its reactivity
C
its density
D
its conductivity
6

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
7

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.
8

In a science lab, Cash mixes two clear liquids together in a beaker. Bubbles are produced, and a white solid forms and settles to the bottom. He plans to heat the beaker over low heat and make more observations.

A
A physical change occurred, so if Cash heats it, the white solid will dissolve to form the original mixture of clear liquids.
B
A physical change occurred, so even if Cash heats it, the white solid will remain.
C
A chemical change occurred, so if Cash heats it, the white solid will dissolve to form the original mixture of clear liquids.
D
A chemical change occurred, so even if Cash heats it, the white solid will remain.
9

What is the outcome of all chemical changes when two substances are combined?

A
A new substance forms with identical properties.
B
The two substances release an odor.
C
The two substances change color.
D
A new substance forms with different properties.
10

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

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Chemical Properties Answers — DAEP-Science 7 A20…