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25 questions
which one is NOT a physical change?
evaporation
boiling
melting
burning
True or false: melting is a chemical change
true
false
Is silver oxidizing (tarnishing) a physical or chemical change?
Physical
Chemical
Which of the following is NOT a clue (evidence) that a chemical reaction has taken place?
Changing size
Changing color
A gas being formed
Formation of a precipitate
Which of the following IS an indicator (evidence) that a chemical change has occurred?
State of matter change
Size Change
Change in temperature
Shape change
John hypothesized that dissolving salt into water produced a chemical reaction because the salt completely disappeared in the water. He dissolved 10g of salt in the 500 mL of water. After leaving the beaker in the sunlight for a few days, the water completely disappeared, and the salt crystals were left in the bottom of the beaker. Based on this observation, John knew his hypothesis was INCORRECT because
The salt failed to completely dissolve in the water
The sunlight caused the chemical reaction to stop
The temperature of the water was below room temperature
The salt and water were separated by a physical process
A student mixed two clear liquids in a beaker, then covered the beaker and let it sit. White crystals formed at the bottom of the beaker. The student concluded that the crystals are a new substance formed by the two liquids. Which of the following observations, if made by the student, MOST supports the student’s conclusion?
The liquid in the beaker remained clear.
The crystals have different properties than the original clear liquids.
The mass of the liquid in the beaker has remained the same
The beaker has not vibrated or move from its original spot.
A student added white crystals to a clear liquid. The crystals dissolve in the liquid. After a few seconds, the liquid became quite warm and then turned bright blue in color. The FIRST indication (piece of evidence) that a chemical change was taking place could be observed when…
The crystals were added to the liquid
The crystals were dissolved in the liquid
The temperature of the liquid increased
The color of the mixture changed
A student watches an ice cube melt into a puddle of water. Has a chemical reaction (chemical change) taken place?
Yes, a gas has been given off
Yes, the color has changed
No, no new substances have formed
No, water does not react chemically
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