Focus On Physical Science: California Grade 8

Unit 3: Chemical Interactions

Unit Tests

1.
Neutral solutions have a pH of ________. 5.e
A)9
B)2
C)7
D)12
2.
What is the pH of a solution? 5.e
A)a measure of the concentration of hydroxide ions in the solution
B)a measure of the concentration of hydronium ions in the solution
C)a measure of the concentration of salts in the solution
D)a measure of the concentration of water molecules in the solution
3.
When a base dissolves in water, _______. 5.e
A)neutralization occurs
B)hydronium ions are produced
C)hydroxide ions are produced
D)a salt is formed
4.
Solutions that conduct an electric current are called _______. 5.e
A)alloys
B)neutral
C)homogeneous
D)electrolytes
5.
A single DNA molecule can contain _______ of atoms. 6.c
A)millions
B)thousands
C)hundreds
D)billions
6.
The most accurate way to measure the pH of a solution is to use _______. 5.e
A)a pH meter
B)an indicator compound
C)red litmus paper
D)blue litmus paper
7.
When baking soda combines with vinegar, _______ occurs. 5.a
A)boiling
B)a physical change
C)a chemical reaction
D)burning
8.
Carbon atoms can form an enormous number of different compounds because _______. 6.a
A)carbon atoms can form ionic and covalent bonds with other atoms
B)carbon is the most abundant element on Earth's surface
C)carbon atoms are larger than most atoms
D)carbon atoms can form covalent bonds with other carbon atoms and other types of atoms in many ways
9.
Which molecule has a tetrahedral shape? 6.a
A)carbon dioxide
B)cyclopentane
C)ethylene
D)methane
10.
Carbohydrates contain only _______ atoms. 6.b
A)carbon, nitrogen, and phosphorus
B)carbon and hydrogen
C)carbon and oxygen
D)carbon, hydrogen, and oxygen
11.
Which is a property of a lipid? 6.c
A)stores genetic information in a cell
B)made from amino acids
C)insoluble in water
D)contain carboxyl groups
12.
Carbon does not form which of these types of bonds? 6.a
A)covalent single
B)ionic
C)covalent double
D)covalent triple
13.
Which is true for an exothermic chemical reaction? 5.c
A)Energy is given off when bonds are broken.
B)The products have more energy stored in their bonds than the reactants have stored in their bonds.
C)The reactants have more energy stored in their bonds than the products have stored in their bonds.
D)Energy is absorbed when bonds are formed.
14.
According to the law of conservation of energy, in a chemical reaction, _______. 5.c
A)energy stored in the reactants is converted into thermal energy
B)energy must be added to the reactants
C)energy stored in the reactants is converted into light
D)energy is neither created or destroyed
15.
Basic solutions have a pH _______. 5.e
A)greater than 7
B)less than 7
C)equal to 14
D)equal to 0
16.
Hydronium ions are produced by the ________. 5.e
A)neutralization of an acid and a base
B)combination of a water molecule and a hydroxide ion
C)combination of a water molecule and a hydrogen ion
D)formation of salts
17.
During a chemical reaction the _______ doesn't change. 5.b
A)number of molecules
B)number of atoms of each element
C)number of compounds
D)formula units
18.
Elements and compounds are _______. 7.c
A)homogeneous mixtures
B)mixtures
C)solutions
D)substances
19.
Which is the most abundant element in the human body? 6.b
A)oxygen
B)nitrogen
C)carbon
D)hydrogen
20.
What is true about an acidic solution? 5.e
A)The concentration of hydronium ions is greater than the concentration of hydroxide ions.
B)The concentration of hydroxide ions is greater than the concentration of hydronium ions.
C)The concentration of hydroxide ions is always equal to the concentration of hydronium ions.
D)Hydronium ions are converted into hydroxide ions.
21.
Oxygen gas is a(n) _______. 3.b
A)compound
B)formula unit
C)diatomic molecule
D)ionic compound
22.
Many of water's unique properties are because it is a _______. 6.c
A)nonpolar molecule
B)polar molecule
C)linear molecule
D)ionic molecule
23.
Which best describes a homogeneous mixture? 7.c
A)It contains only one substance.
B)The substances are bonded together on the atomic level.
C)Its composition can vary from place to place in the mixture.
D)The substances are evenly mixed on the atomic level.
24.
Which is the best description of an unsaturated fat? 6.a
A)It contains no water
B)It has only single bonds between carbon atoms
C)It has at least one double bond between carbon atoms
D)It is a solid at room temperatures.
25.
Which is a balanced chemical equation? 5.b
A)2K + Br2 ? 2KBr
B)K + Br2 ? 2KBr
C)2K + 2Br2 ? 2KBr
D)K + Br2 ? KBr
26.
All living organisms need which compound in order to live? 6.c
A)water
B)methane
C)isopropyl alcohol
D)lactic acid
27.
Which of these is a chemical change? 5.a
A)melting
B)boiling
C)dissolving
D)rusting
28.
Which type of compound is not a monomer? 3.c
A)amino acids
B)sugars
C)hydrocarbons
D)nucleotides
29.
A _______ is a molecule composed of two or more different atoms. 3.b
A)element
B)compound
C)reactant
D)product
30.
Which is a substance that is formed by chemical reaction? 5.a
A)reactant
B)compound
C)element
D)product
31.
Which is a chemical reaction between an acid and a base in which a salt and water are formed? 5.e
A)hydration
B)acidification
C)neutralization
D)salination
32.
All acidic solutions contain _______. 5.e
A)hydronium ions
B)hydroxide ions
C)metallic ions
D)salts
33.
How many hydrogen atoms are in the compound CH2(OH)2? 5.b
A)six
B)two
C)three
D)four
34.
The six most abundant elements in living organisms include carbon, oxygen, nitrogen, and hydrogen, as well as _______. 6.b
A)sodium and magnesium
B)phosphorus and sulfur
C)sodium and chlorine
D)sodium and calcium
35.
Which is not a complex carbohydrate? 6.c
A)glycogen
B)cellulose
C)nucleic acid
D)starch
36.
Which best describes a solution with a pH of 6.4? 5.e
A)strongly basic
B)strongly acidic
C)slightly basic
D)slightly acidic
37.
A _______ is a combination of two or more substances that can be separated by physical means. 7.c
A)substance
B)compound
C)element
D)mixture
38.
Which is true when a chemical reaction occurs? 5.a
A)New substances are produced.
B)A material changes from a solid to a liquid.
C)Materials mix evenly with each other.
D)The change can be easily reversed.
39.
Which happens to the number of atoms in a chemical reaction? 5.b
A)The number of atoms increases
B)The number could increase or decrease, depending on the chemical reaction.
C)The number of atoms doesn't change.
D)The number of atoms decreases.
40.
When chemical bonds are formed, ________. 5.c
A)energy is absorbed
B)energy is released
C)the reaction is endothermic
D)the reaction is exothermic
41.
Which best describes the law of conservation of mass? 5.b
A)The total mass decreases if the reaction is endothermic.
B)The total mass increases if the reaction is exothermic.
C)A chemical reaction produces mass.
D)The mass of the reactants always equals the mass of the products.
42.
One use of water in plants and animals is _______. 6.c
A)to convert hydrocarbons to polar molecules
B)to convert carbon dioxide to water vapor
C)to transport nutrients to cells
D)to form organic compounds
43.
A saturated hydrocarbon contains only _______ between the carbon atoms. 6.a
A)single covalent bonds
B)single ionic bonds
C)single and double covalent bonds
D)triple covalent bonds
44.
Which of the following acts as a base by accepting a hydrogen ion from water? 5.e
A)vinegar
B)magnesium hydroxide
C)sodium hydroxide
D)ammonia
45.
A chemical reaction that absorbs energy _______. 5.c
A)is an exothermic reaction
B)is an endothermic reaction
C)violates the law of conservation of energy
D)violates the law of conservation of mass
Grade 8
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