Online Assessment
Instructions
1) Type in your first and last name in the
“Name” box in the top-left corner.
2) Next type in your teacher’s name in
the “ID” box.
3) Then type in your school’s full name in the
“Email” box.
4) Select the best answer for each question.
5) When you
are finished click the “Grade and Submit” button.
6) The grade will be emailed
to your teacher.
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1.
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NOTE: If your teacher’s last
name is Elliott, then you are doing the wrong assessment.
---This assessment is only for
students of other teachers.
---If your teacher is Mr. Elliott, then please go back to the
website and click on the first assessment link instead. Thanks!
No matter is created or destroyed in any reaction according to the law of
conservation of mass.
Which sample equation best illustrates the law of
conservation of mass?
a. | 4 grams reactant U + 3 grams reactant V à 7 grams product W | b. | 12 grams reactant
X + 10 grams reactant Y à 2 grams product
Z | c. | 5 grams reactant E + 5 grams reactant F à 20 grams product G | d. | 10 grams reactant
Q + 9 grams reactant R à 90 grams product S
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2.
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A
student observes a chemical reaction. | Aluminum (Al) + Oxygen (O)
yields Aluminum Oxide (Al2O3) | |
She writes an equation that correctly displays the law of conservation of
mass.
Select the balanced equation below that she wrote about this chemical
reaction.a. | 4Al + 3O2  2Al2O3 | c. | 2Al + 3O3  2Al2O3 | b. | 4Al +
2O2  3Al2O3 | d. | Al +
O2  Al2O3 |
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3.
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No mass is created or destroyed in chemical
reactions according to the law of conservation of mass.
Which procedure best represents
the law of conservation of mass?
a. | exploding a 30g stick of dynamite leaving behind only a
5g piece of the stick | b. | boiling 10 grams
of salt water | c. | using a magnet to
separate 5 grams of metal flakes from 10 grams of sand | d. | combining 6g of hydrogen & 3g of oxygen to produce 9g of dihydrogen
monoxide |
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4.
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Students have two
identical beakers with a mass of 20 grams each. The students pour a different liquid reactant into
each beaker. The total mass of the two beakers with the reactants is 50 grams. Next, the students
combine Reactant 1 and Reactant 2 into one of the beakers. A chemical reaction produces a
product.
If all of the reactants are consumed and no gases are produced, what is the
total mass of the product and one beaker?
a. | 30
grams | b. | 40
grams | c. | 20
grams | d. | 70
grams |
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5.
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A copper bar with a mass of 80 grams was left
outside under a tree. Oxygen in the air reacted with the bar forming rust called copper oxide. As the
bar rusted, its mass increased.
Choose the answer below that best explains how the mass
increased.
a. | The copper oxide released heat which caused the bar to
expand. | b. | Oxygen atoms combined with the copper atoms as the rust
was forming. | c. | Rust grew as it
absorbed energy from the copper bar | d. | Water was absorbed
as the rust formed on the copper bar. |
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6.
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A student asks why the ashes from a fire have a
much lower mass than the wood that was burned.
Which is the correct answer to the
students question?
a. | Heat causes molecules to lose
density. | b. | Gases are released into the
air. | c. | Water inside the wood
solidifies. | d. | Atoms in the wood
are destroyed. |
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7.
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Four Chemical Equations | 3S +
2O 3  3SO 2 | C3H8 + 5O2  4H2O + CO | 2N 2 + O 2
2N 2O | 2H 2 + O 2 
2H 2O | |
Three of the equations listed above
demonstrate the law of conservation of mass.
One of them, however, is an unbalanced equation.
Identify the unbalanced equation. a. | C3H8 +
5O2  4H2O +
CO | c. | 2H2 + O2
2H2O | b. | 3S +
2O3 
3SO2 | d. | 2N2 + O2
2N2O |
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8.
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The reaction below shows potassium oxide being
produced (KO2) by combining
oxygen (O2) with potassium (K). The
mass of potassium is 50 grams and the mass of oxygen is 12 grams.
O2 + K  KO2
What is the mass for the potassium oxide that was
produced?
a. | 12
grams | b. | 50
grams | c. | 160
grams | d. | 62
grams |
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9.
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In the equation below,
46 grams of sodium (Na) reacted with 36 grams of water (H2O).
If 2 grams of hydrogen gas (H2) is produced by this reaction, what is the mass of sodium hydroxide
(NaOH) produced?
a. | 44
grams | b. | 82
grams | c. | 10
grams | d. | 80
grams |
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10.
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A chemical reaction occurs when you cook outside
using a propane grill.
The reactants are propane (C3H8) and oxygen
(O2).
The products are water (H2O) and carbon dioxide
(CO2)
Which equation correctly represents
this reaction?
a. | CH8 + 5O2
 4H2O +
3CO2 | b. | C3H8 + 5O2  4H2O + CO | c. | C3H8 + O2  4H2O + 3CO2 | d. | C3H8 + 5O2  4H2O + 3CO2 |
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