Chemical Properties Answers

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1
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Which characteristic of a substance is considered a chemical property?

A
its boiling point
B
its reactivity
C
its density
D
its conductivity
2
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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.
4

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.
5

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
8

Which use of iron is due to its chemical properties?

A
producing colored sparks in fireworks
B
changing from liquid to gas at 2,862°C
C
conducting electricity and heat
D
changing from solid to liquid if heated to 1,538°C
9

Which event always involves a chemical change?

A
boiling
B
melting
C
conducting
D
burning
10

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
11

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.
12

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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