Download Law of Conservation of Mass Quiz

OBJ 25 Quiz-LOCOM
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. 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 student’s question?
a. Gases are released into the air.
b. Atoms in the wood are destroyed.
c. Heat causes molecules to lose density.
d. Water inside the wood solidifies.
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2. 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. 40 grams
b. 30 grams
c. 20 grams
d. 70 grams
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3. 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. 10 grams
b. 44 grams
c. 80 grams
d. 82 grams
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4. The reaction below shows potassium oxide being produced (KO2) by combining
oxygen (O2) with potassium (K). The mass of potassium is 50 g and the mass of oxygen is 12 g.
O2 + K
KO2
What is the mass for the potassium oxide that was produced?
a. 160 grams
b. 62 grams
c. 12 grams
d. 50 grams
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5. 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. 2Al + 3O3
2Al2O3
c. Al + O2
Al2O3
b. 4Al + 2O2
3Al2O3
d. 4Al + 3O2
2Al2O3
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6. A chemical equation is shown below.
____
Which substance is a reactant?
a. Diydrogen Monoxide
b. H2O
7. A chemical equation is shown below.
2H2O 2H2 + O2
c. Hydrogen
d. Water
2H2O 2H2 + O2
Which of the following choices is the product of this chemical reaction?
a. Hydrogen
c. H2
b. Water
d. Oxygen
____
8. Examine the following chemical reaction
Iron (Fe) reacts with Oxygen (O) to form iron oxide (FeO) which is commonly called rust.
2Fe + 3O2
2FeO3
Which chemical formula shown below is the product of this reaction?
a. Iron (Fe)
b. Iron Oxide
c. 3O2
d. 2FeO3
____
9. A chemical equation is shown below.
2NaCl +2H2O Cl2 + H2 + 2NaOH
Which substance is a reactant?
a. NaCl
b. Cl
c. NaOH
d. H2
____ 10. A balanced chemical equation is shown below.
2PbO + 4NO2 + O2  2Pb(NO3)
The product in this equation is...?
a. O2
b. PbO
c. NO2
d. Pb(NO3)2
____ 11. Examine the four noble gases mentioned in the question below.
Notice the elements in the far-right: Helium (He), Neon (Ne), Argon (Ar), and Krypton (Kr).
Determine what group number they are in, and determine how many electron shells krypton
has.
a. Group 4, 6 electron shells
c. Group 18, 4 electron shells
b. Group 18, 7 electron shells
d. Group 7, 8 electron shells
____ 12. Three elements are shaded in this periodic table: Nitrogen (N), Oxygen (O), and Fluorine (F)
Which statement best describes all three shaded elements shown above?
a. They all have the same atomic numbers and the same atomic mass.
b. They are all in period 4, so they all have 4 electron shells.
c. They all are metals in the second period.
d. They are all in period 2, so they all have 2 electron shells.
____ 13. Look at the diagram below of one Boron (B) atom.
Two-Part Question
a) Based on the number of valence electrons, what group number is boron found in?
b) Based on the number of electons shells, what period number is boron found in?
a. Group 13, Period 5
c. Group 2, Period 13
b. Group 3, Period 3
d. Group 13, Period 2
____ 14. A periodic table of the elements is shown below.
Based on their locations on the periodic table, which two elements share the most similar
chemical properties?
a. He and Li
b. H and Kn
c. K and Ca
d. Ne and Xe
____ 15.
Use the Periodic Table above in question 14 to answer the following question.
How many protons does the element Neon (Ne) have and how many electron shells does it
have?
a. 8 protons, and 10 electron shells
c. 10 protons, and 2 electron shells
b. 2 protons, and 8 electron shells
d. 10 protons, and 18 electron shells