Physical Science

Chapter 21: Chemical Reactions

Chemical Reactions

1.
What type of reaction produces a precipitate?
A)synthesis
B)single displacement
C)double displacement
D)decomposition
2.
__________ is a way to describe a chemical reaction using chemical formulas and symbols.
A)Synthesis
B)A physical law
C)The law of conservation of matter
D)A chemical equation
3.
An insoluble compound that comes out of solution during a double displacement reaction is called a __________ .
A)reactant
B)solvent
C)precipitate
D)catalyst
4.
What does it mean for a chemical equation to be balanced?
A)The number of reactants is equal to the number of products.
B)The reactants and the products are written with the same coefficients.
C)The same number of atoms of each element is on both sides of the equation.
D)The solid products weigh the same as the reactants.
5.
In chemical equations, __________ represent the number of units of each substance.
A)precipitates
B)products
C)reactants
D)coefficients
6.
The chemical formula for a compound tells __________ .
A)how stable the compound is
B)what type of chemical bond it forms
C)how electrons are arranged
D)what elements it contains
7.
If electric current passes through water and initiates a decomposition reaction, what are the expected products?
A)oxygen and water
B)hydrogen and oxygen
C)hydrogen peroxide
D)hydrogen oxide
8.
When iron combines with oxygen and water in the air to form rust, what substance in the reaction is the product?
A)iron
B)rust
C)water
D)oxygen
9.
As a result of the experiments of Lavoisier, you know that in a chemical reaction the mass of the products __________.
A)is less than the mass of the reactants
B)always equals the mass of the reactants
C)cannot be predicted based on the mass of the reactants
D)is twice as great as the mass of the reactants
10.
Ten grams of mercury(II) oxide react to produce 9.3 g of mercury and oxygen. What is the mass of the oxygen produced?
A)19.3 g
B)1.7 g
C)7.0 g
D)0.7 g
11.
New substances produced by a chemical reaction are __________ .
A)products
B)resultants
C)reactants
D)coefficients
12.
In a __________ reaction, two or more substances combine to form another substance.
A)single displacement
B)double displacement
C)decomposition
D)synthesis
13.
A change in which one or more substances are converted into new substances is a __________ .
A)nuclear reaction
B)chemical reaction
C)chemical fusion
D)physical change
14.
A(n) __________ is a substance that speeds up a chemical reaction without being permanently changed itself.
A)catalyst
B)inhibitor
C)exotherm
D)endotherm
15.
Why is oxygen written with a subscript 2?
A)It usually exists as a diatomic molecule.
B)Its mass is twice as great as the reactants'.
C)There are two times as many oxygen atoms as reactant atoms.
D)Its mass increases by two times as a result of the reaction.
16.
The law of conservation of mass states that __________ .
A)in a chemical reaction, matter is not created or destroyed, but is conserved
B)matter can be created and destroyed but does not change forms
C)in a chemical reaction, efforts should be made to preserve rare elements without changing them
D)in a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants
17.
Which of the following is a chemical reaction?
A)water freezing into ice
B)water evaporating from salt water leaving salt crystals
C)dew forming on grass
D)rust forming on a car body
18.
Some elements usually exist in combinations of two atoms. These combinations are called __________ .
A)diatomic molecules
B)coefficients
C)ions
D)isotopes
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