Chemical Equations and Reactions

Assessment
•
Mary Marisa
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Science, Chemistry
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10th Grade
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335 plays
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Medium
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15 questions
Show answers
1.
Multiple Choice
Which of the following is true regarding the law of conservation of mass?
It dictates that the number of molecules on each side of a chemical equation must be the same.
It dictates that the number of atoms of each element must be the same on both sides of a chemical equation.
It states that the mass of the reactants must remain constant in order for a chemical reaction to proceed.
It does not apply to chemical reactions.
Answer explanation
The number of molecules does not have to be the same because lots of molecules could be needed to make one new one. However, the number of each type of atom does need to be the same.
2.
Multiple Choice
Which of the following may indicate that a chemical reaction has occured?
release of energy as light
a color change
gas bubble formation
all of these
3.
Multiple Choice
Which of the following is a product in the reaction described by the word equation: iron + copper(II) sulfate --> iron(II) sulfate + copper
iron(II) sulfate
copper
iron
two of these are correct
Answer explanation
Iron(II) sulfate and copper are both products of this chemical reaction. Products are substances produced by the chemical reaction that are pointed to by the arrow.
4.
Multiple Choice
What does CH4 represent in the balanced chemical equation: C + 2 H2 --> CH4
1 atom CH4
5 atoms CH4
1 molecule CH4
1 g CH4
Answer explanation
Balanced chemical equations can be interpreted in terms of molecules of a compound or moles of a compound.
5.
Multiple Choice
Which of the following is NOT true regarding a properly written chemical equation?
It must be balanced.
It must contain proper chemical formulas.
It must show the formation of a precipitate or a gas.
It should represent known data.
Answer explanation
There are many signs that a chemical reaction has taken place. Formation of a precipitate or a gas is not required, but could be an indicator that a reaction has occurred.
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