WorksheetsReview Unit 2
Total questions: 36
Worksheet time: 3hrs 0mins
Strontium phosphate, Sr.(PO4)2, is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for Sr3(PO4)2?
2
3
4
The table shows the chemical formulas for four substances. Which substances have the same number of carbon atoms?
Substances 1 and 2
Substances 2, 3, and 4
Substances 2 and 3 only
Substances 1 and 3
Which of these formulas contain equal numbers of nitrogen atoms?
Formulas I and III
Formulas I and IV
Formulas II and III
Formulas I, II, and V
The equation below represents a chemical reaction that occurs in living cells. How many atoms are represented in the reactants of this equation?
6
12
24
36
In which of these compounds are there twice as many oxygen atoms as hydrogen atoms?
f
g
H
j
The chemical formula for sodium sulfate is Na₂SO₂. How many sulfur atoms are in the formula for sodium sulfate?
1
2
6
7
A student obtains two strips of magnesium, Mg, ribbon that are each 3 cm long. One strip of magnesium is placed in a test tube containing 5 mL of water, and the other strip is placed in a test tube containing 5 mL of hydrochloric acid, HCI. Both liquids are at room temperature. The student's observations are recorded in the table. Which statement is not supported by the student's observations?
A chemical reaction takes place between magnesium and hydrochloric acid.
A gas is released in Test Tube 2.
The substances in both test tubes are reactive only at high temperatures.
Energy is released in the reaction involving hydrochloric acid.
Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?
the shape changes
oxygen is present
a new substance is produced
coal is made up of more than one element
Nitrogen dioxide is a gas that can be generated by emissions from vehicles and factories. It can also be generated by natural sources, such as forest fires, lightning, and microbial activity in soil. The equation for producing nitrogen dioxide is shown below. Which of these provides evidence that a chemical reaction occurs?
A gas is present.
The total number of atoms remains unchanged.
The state of matter remains the same.
A brown gas is produced.
All the following reactions are correctly balanced except -
F
G
H
J
A scientist spilled a few drops of dilute hydrochloric acid (HCI) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO3) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?
The baking soda and hydrochloric acid combined, and bubbles formed.
The baking soda absorbed the hydrochloric acid.
Some of the baking soda dissolved in the hydrochloric acid.
The hydrochloric acid evaporated, leaving only the baking soda.
For an investigation a student poured a blue solution of CuSO4 into a beaker. The student placed a shiny, silver-colored strip of zinc metal in the solution and observed the changes. Observations of an Investigation The student inferred that a chemical reaction occurred. What evidence supports this inference?
A dark solid formed on the zinc metal.
The zinc metal remained silver-colored and shiny.
The CuSO solution turned blue when the zinc metal was added.
None of these
Some Students in a chemistry lab conducted an investigation in which they added four different solid substances to separate beakers of water. They stirred the mixtures for one minutes and recorded their observations on the table. Which Substance most likely created a new substance to be formed when mixed with water.
substance 1
substance 2
substance 3
substance 4
Many Processes occur in the digestive system. Which process is best classified as a physical change?
Saliva converting the starch molecules in crackers into simple sugars
Digestive enzymes breaking down proteins into smaller fragments
Bacteria converting lactose into simple sugars in the intestines
Teeth grinding an almond into smaller pieces in the mouth
A teacher asks a student to write the chemical equation for photosynthesis. The student's response is shown below. The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?
During an investigation, a student combined the two clear, colorless solutions shown below. The student observed that the temperature changed from 25°C to 23°C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?
One of the original compounds came out of solution.
The solutions reacted chemically.
Some of the water froze into ice crystals.
Rapid evaporation of water occurred, leaving a solid.
A student mixed a solution of sodium hydroxide (NaOH) with hydrochloric acid (HCl) in a beaker. The temperature of the solution increased. What does this observation suggest?
The reaction is endothermic.
The reaction is exothermic.
No reaction occurred.
The reaction is neutral.
A student added a piece of zinc to a solution of copper sulfate. The color of the solution changed from blue to colorless. What does this indicate?
A physical change occurred.
A chemical change occurred.
No change occurred.
The zinc dissolved in the solution.
A chemical formula is shown below. The subscripts in a chemical formula represent the-
NaNO2
A. number of atoms of the element in front of the subscript.
B. atomic mass of the heaviest element in the compound.
C. atomic number of the element that follows the subscript.
D. column on the Periodic Table of the element next to it.
H2 + O → H2O
The Law of Conservation of Mass states that -
the number and type of atoms on both sides of a chemical reaction are equal
there are more atoms on the reactant side than the product side
there are more atoms on the product side than the reactant side
the mass of the product will not equal the reactants
You know you a chemical reaction has occurred if:
there is a precipitate.
there is a permanent color change.
there is a temperature change.
All of these answers are evidence.
Match for Na(HCl3)4
1
Number of Sodium
4
Number of Hydrogen
12
Number of Chlorine
3
Number of Elements
Match the element to the number of atoms it has.
2 Al(C2H3O4)2
aluminum
2
carbon
8
hydrogen
12
oxygen
16
Put the elements in order from smallest to largest number of atoms:
2 C3H5(NO3)4
carbon
nitrogen
hydrogen
oxygen
Can compounds be found in the periodic table?
Yes
No
How many total atoms are in the compound, 2Na(OH)2?
(a)
How many total atoms are in 6H2SO4?
(a)
A compound secreted by honeybees to paralyze intruders in their hive is known as 2-heptanone. The formula for this compound is:
CH3C4H8COCH3
How many atoms of each element are in one molecule of 2-heptanone?
(a) carbon atoms, (b) hydrogen atoms, and (c) oxygen atom
Which chemical reaction involves the fewest oxygen atoms?
