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10 questions
Heat is always a sign of a chemical reaction.
True
false
A chemical reaction occurs that involves combining 1 atom of zinc with 2 atoms hydrogen and 2 atoms of chlorine. After the reaction, how many atoms of each element will there be?
2 zinc, 2 hydrogen, 2 chlorine
1 zinc, 2 hydrogen, 2 chlorine
2 zinc, 1 hydrogen, 2 chlorine
3 zinc, 2 hydrogen, 2 chlorine
Two chemicals are combined in a beaker and react. What data would provide the best evidence for determining if the reaction absorbed or released thermal energy?
The masses of the substances before and after the reaction.
The temperature inside the beaker before and after the reaction.
Whether or not light and sound were produced during the reaction.
How long it took for the reaction to take place once the chemicals combined.
Which of the following is true regarding the atoms involved in a chemical reaction?
Some of the atoms present before the reaction will always be always be lost during a chemical reaction.
Some of the atoms will always be changed into a different type of atom by a chemical reaction.
During a chemical reaction, atoms will always be combined into much larger molecules.
The same number of each type of atom will always be present before and after a chemical reaction takes place.
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