8th Grade Final Exam Practice Test
Some people have a hard time in chemistry class, especially when it comes to equations and naming elements in a reaction. Are you an 8th grader preparing for your end of year exam? If so, then the practice test below is exactly what you need to get the high grade you desire. Give it a shot and all the best in the finals.
- 1.
Select 2 terms to describe this diagram.
- A.
Element
- B.
Compound
- C.
Single atoms
- D.
Molecule
Correct Answer(s)
A. Element
C. Single atomsExplanation
The diagram likely represents a collection of individual atoms, as indicated by the term "single atoms." These atoms are most likely representing elements, which are substances made up of only one type of atom. Therefore, the two terms that best describe the diagram are "element" and "single atoms."Rate this question:
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- 2.
Choose 2 terms to describe this diagram
- A.
Element
- B.
Compound
- C.
Single atoms
- D.
Molecule
Correct Answer(s)
B. Compound
D. MoleculeExplanation
The diagram includes two terms: compound and molecule. A compound refers to a substance made up of two or more different elements chemically bonded together. On the other hand, a molecule refers to a group of two or more atoms held together by chemical bonds. Both terms are related to the combination of elements, but a compound specifically involves different elements while a molecule can involve the same or different elements.Rate this question:
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- 3.
Select 2 terms to describe this diagram
- A.
Element
- B.
Compound
- C.
Single atoms
- D.
Molecule
Correct Answer(s)
A. Element
D. MoleculeExplanation
The diagram likely represents a combination of single atoms and molecules. An element refers to a substance that is composed of only one type of atom, while a molecule is formed when two or more atoms are chemically bonded together. Therefore, the terms "element" and "molecule" accurately describe the components in the diagram.Rate this question:
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- 4.
Which diagram correctly shows the molecule according to the formula given?
- A.
Option 1
- B.
Option 2
- C.
Option 3
- D.
Option 4
Correct Answer
D. Option 4 -
- 5.
Which of the following formulas correctly describes the molecule in the diagram?
- A.
CaCO3
- B.
CaCOOO
- C.
CaCO5
- D.
CaCO
Correct Answer
A. CaCO3Explanation
The correct answer is CaCO3 because it represents the chemical formula for calcium carbonate. Calcium carbonate is a compound composed of one calcium atom (Ca) and three carbonate ions (CO3). The formula CaCOOO is incorrect as it does not follow the proper chemical notation. CaCO5 is also incorrect as it suggests the presence of five carbonate ions, which is not the case. CaCO is also incorrect as it does not specify the number of carbonate ions present.Rate this question:
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- 6.
According to the diagram, which of the following are the reactants?
- A.
H2O
- B.
NH4+
- C.
NH3
- D.
OH-
Correct Answer(s)
A. H2O
C. NH3Explanation
The reactants in a chemical reaction are the substances that undergo a chemical change. In the given options, H2O (water) and NH3 (ammonia) are the reactants because they are the substances that are present before the reaction takes place. NH4+ (ammonium) and OH- (hydroxide) are not reactants in this context as they are not mentioned in the question or diagram.Rate this question:
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- 7.
According to the diagram, which of the following are the products?
- A.
H2O
- B.
NH4+
- C.
NH3
- D.
OH-
Correct Answer(s)
B. NH4+
D. OH-Explanation
NH4+ and OH- are the products according to the diagram. This can be determined by analyzing the chemical reactions depicted in the diagram. NH4+ is a positively charged ion formed by the combination of NH3 (ammonia) with a hydrogen ion (H+). OH- is a negatively charged ion formed by the dissociation of H2O (water) into a hydroxide ion (OH-) and a hydrogen ion (H+). Therefore, NH4+ and OH- are the products indicated in the diagram.Rate this question:
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- 8.
Does the equation in this diagram show a chemical reaction?
- A.
Yes, because there's an arrow
- B.
Yes, because the reactants are different from the products
- C.
No, because the reactants had to break their chemical bonds
- D.
No, because the reactants are different from the products
Correct Answer
B. Yes, because the reactants are different from the productsExplanation
The correct answer is Yes, because the reactants are different from the products. In a chemical reaction, the reactants are transformed into different substances, which are the products. The fact that the reactants and products are different indicates that a chemical reaction has occurred. The presence of an arrow in the equation also suggests a chemical reaction, as it represents the direction of the transformation.Rate this question:
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- 9.
According to this diagram, did a chemical reaction occur?
- A.
Yes, because chemical bonds were broken and/or formed
- B.
Yes, because chemical bonds were NOT broken and/or formed
- C.
No, because chemical bonds were broken and/or formed
- D.
No, because chemical bonds were NOT broken and/or formed
Correct Answer
A. Yes, because chemical bonds were broken and/or formedExplanation
The correct answer is "Yes, because chemical bonds were broken and/or formed." This is because chemical reactions involve the breaking and/or forming of chemical bonds between atoms. In the diagram, if there is evidence of broken or formed chemical bonds, it indicates that a chemical reaction has occurred.Rate this question:
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- 10.
Does this diagram show a chemical reaction?
- A.
Yes, because chemical bonds were broken and/or formed
- B.
Yes, because chemical bonds were NOT broken and/or formed
- C.
No, because chemical bonds were broken and/or formed
- D.
No, because chemical bonds were NOT broken and/or formed
Correct Answer
D. No, because chemical bonds were NOT broken and/or formedExplanation
The correct answer is No, because chemical bonds were NOT broken and/or formed. This means that there was no chemical reaction occurring. Chemical reactions involve the breaking and/or forming of chemical bonds, so if no bonds were broken or formed, it indicates that there was no chemical reaction taking place in the diagram.Rate this question:
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- 11.
Are these two liquids soluble or insoluble?
- A.
Soluble because one is floating on top of the other
- B.
Soluble because they are mixing
- C.
Insoluble because they are not mixing
- D.
Insoluble because they are able to dissolve
Correct Answer
C. Insoluble because they are not mixingExplanation
The correct answer is insoluble because they are not mixing. When two liquids are soluble, they are able to mix together completely, forming a homogeneous solution. In this case, since the liquids are not mixing and one is floating on top of the other, it suggests that they are not soluble and therefore insoluble.Rate this question:
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- 12.
Which of the following statements is true? Check all that apply
- A.
Cotton is synthetic because you can see that it is grown on a farm
- B.
Polyester is synthetic because you can see that it's made in a factory
- C.
Polyester is synthetic because they use it to make jerseys
- D.
Cotton is natural because it comes from a plant
Correct Answer(s)
B. Polyester is synthetic because you can see that it's made in a factory
D. Cotton is natural because it comes from a plantExplanation
The answer is correct because polyester is indeed synthetic as it is manufactured in a factory using chemical processes. On the other hand, cotton is natural as it is derived from the cotton plant.Rate this question:
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- 13.
Which state of matter is this?
- A.
Solid
- B.
Liquid
- C.
Gas
- D.
None of the above
Correct Answer
C. GasExplanation
The given state of matter is gas. This is because gases have no fixed shape or volume, and they can easily expand to fill the space available to them.Rate this question:
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- 14.
Which state of matter is this?
- A.
Solid
- B.
Liquid
- C.
Gas
- D.
None of the above
Correct Answer
A. SolidExplanation
The given question is asking about the state of matter being represented. The answer is "Solid" because solids have a definite shape and volume, and their particles are tightly packed together and vibrate in fixed positions.Rate this question:
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- 15.
Which state of matter is this?
- A.
Solid
- B.
Liquid
- C.
Gas
- D.
None of the above
Correct Answer
B. LiquidExplanation
The given state of matter is liquid. This is because liquids have a definite volume but no definite shape. They can flow and take the shape of their container. The other options, solid and gas, do not fit the description given in the question.Rate this question:
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- 16.
Which statements correctly describes the relationship between temperature and the speed of atoms? Check all that apply
- A.
As temperature increases, atoms move more slowly
- B.
As temperature increases, atoms move more quickly
- C.
As temperature decreases, atoms move more slowly
- D.
There is no relationship between temperature and the speed of atoms
Correct Answer(s)
B. As temperature increases, atoms move more quickly
C. As temperature decreases, atoms move more slowlyExplanation
As temperature increases, atoms move more quickly because an increase in temperature corresponds to an increase in the kinetic energy of the atoms. This increase in kinetic energy causes the atoms to vibrate and move more rapidly. On the other hand, as temperature decreases, atoms move more slowly because a decrease in temperature corresponds to a decrease in the kinetic energy of the atoms. This decrease in kinetic energy causes the atoms to have less vibrational and translational motion, resulting in slower movement. Therefore, both statements accurately describe the relationship between temperature and the speed of atoms.Rate this question:
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- 17.
Which of the following statements correctly describes the relationship between temperature and the volume of a substance?
- A.
As temperature increases, volume increases
- B.
As temperature increases, volume decreases
- C.
As temperature decreases, volume increases
- D.
There is no relationship between temperature and the volume of a substance
Correct Answer
A. As temperature increases, volume increasesExplanation
As the temperature of a substance increases, the kinetic energy of its particles also increases. This increased kinetic energy causes the particles to move more rapidly and spread out, resulting in an increase in the volume of the substance. Therefore, the statement "As temperature increases, volume increases" correctly describes the relationship between temperature and volume of a substance.Rate this question:
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- 18.
Charles has a balloon full of helium. If Charles heats the helium inside of the balloon, which of the following things should happen?
- A.
The atoms inside the balloon will get bigger, so the balloon will get bigger
- B.
The atoms inside the balloon will spread out more, so the balloon will get bigger
- C.
The helium will undergo a chemical reaction and the balloon will pop
- D.
The atoms inside the balloon will slow down and the balloon will shrink
Correct Answer
B. The atoms inside the balloon will spread out more, so the balloon will get biggerExplanation
When Charles heats the helium inside the balloon, the atoms inside the balloon will gain energy and move faster. This increased kinetic energy causes the atoms to spread out more, leading to an expansion in volume. As a result, the balloon will get bigger.Rate this question:
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- 19.
Which of the following statements is shown in this diagram?
- A.
In a chemical reaction, the mass of the reactants is equal to the mass of the products
- B.
In a chemical reaction, the mass of the reactants is greater than the mass of the products
- C.
In a chemical reaction, atoms are neither gained nor lost
- D.
In a chemical reaction, atoms can be lost, but you can always get them back
Correct Answer(s)
A. In a chemical reaction, the mass of the reactants is equal to the mass of the products
C. In a chemical reaction, atoms are neither gained nor lostExplanation
The diagram shows a balanced chemical equation, where the number of atoms on both sides of the reaction is equal. This indicates that in a chemical reaction, atoms are neither gained nor lost. Additionally, the law of conservation of mass states that the mass of the reactants is equal to the mass of the products, further supporting the answer choice.Rate this question:
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- 20.
Which of the following statements about chemical reactions are FALSE? Check all that apply
- A.
Chemical reactions always result in the formation of new substances
- B.
In a chemical reaction, the physical properties of the products will be the same as those of the reactants
- C.
In a chemical reaction, the physical properties of the products will be different from those of the reactants.
- D.
Chemical reactions sometimes result in the formation of new substances.
Correct Answer(s)
B. In a chemical reaction, the physical properties of the products will be the same as those of the reactants
D. Chemical reactions sometimes result in the formation of new substances.Explanation
The first statement is false because not all chemical reactions result in the formation of new substances. Some reactions may only involve a rearrangement of atoms or molecules without producing new compounds. The third statement is also false because chemical reactions can indeed result in the formation of new substances, such as when two or more elements combine to form a compound.Rate this question:
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- 21.
Which of the following physical properties can be used to identify a substance? Check all that apply.
- A.
The melting point
- B.
The boiling point
- C.
The density
- D.
The solubility
Correct Answer(s)
A. The melting point
B. The boiling point
C. The density
D. The solubilityExplanation
The melting point, boiling point, density, and solubility are all physical properties that can be used to identify a substance. The melting point is the temperature at which a substance changes from a solid to a liquid state, while the boiling point is the temperature at which a substance changes from a liquid to a gas state. Density is a measure of how much mass is contained in a given volume of a substance. Solubility refers to the ability of a substance to dissolve in a solvent. By analyzing these properties, scientists can determine the identity of a substance.Rate this question:
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- 22.
This image shows that the majority of the iron shavings are collecting around the...
- A.
Magnet
- B.
Magnetic poles
- C.
Magnetic axis
- D.
Magnetic towers
Correct Answer
B. Magnetic polesExplanation
The image indicates that the iron shavings are clustering around certain areas. These areas are most likely the magnetic poles of the magnet. Magnetic poles are the regions of a magnet where the magnetic field is strongest, and they attract magnetic materials like iron. Therefore, it can be inferred that the majority of the iron shavings are collecting around the magnetic poles of the magnet.Rate this question:
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- 23.
At which point does the roller coaster have the MOST gravitational potential energy?
- A.
A
- B.
B
- C.
C
- D.
None of the above
Correct Answer
A. AExplanation
The roller coaster has the most gravitational potential energy at point A because it is at the highest point of the track. At this point, the roller coaster has the maximum height and therefore the maximum potential energy due to gravity. As the roller coaster moves downwards, its potential energy decreases and is converted into kinetic energy.Rate this question:
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- 24.
At which point does the roller coaster have the LEAST gravitational potential energy?
- A.
A
- B.
B
- C.
C
- D.
None of the above
Correct Answer
B. BExplanation
The roller coaster has the least gravitational potential energy at point B. This is because gravitational potential energy is directly proportional to the height of an object above the reference point. At point B, the roller coaster is at its lowest height, which means it has the least gravitational potential energy compared to points A and C.Rate this question:
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- 25.
During an exothermic reaction, temperature...
- A.
Increases
- B.
Decreases
- C.
Stays the same
- D.
Decreases, then increases
Correct Answer
A. IncreasesExplanation
During an exothermic reaction, the reactants release energy in the form of heat to the surroundings. This increase in energy causes the temperature to rise, resulting in an increase in temperature. Therefore, the correct answer is "Increases."Rate this question:
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- 26.
During an exothermic reaction, energy is...
- A.
Absorbed
- B.
Released
- C.
Neither absorbed nor released
- D.
Both absorbed and released
Correct Answer
B. ReleasedExplanation
During an exothermic reaction, energy is released. This means that the reaction releases heat or energy into its surroundings. Exothermic reactions typically involve the formation of new bonds, resulting in the release of energy that was previously stored in the chemical bonds of the reactants. This release of energy is often observed as an increase in temperature or the production of light.Rate this question:
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- 27.
During an endothermic reaction, temperature...
- A.
Increases
- B.
Decreases
- C.
Stays the same
- D.
Increases, then decreases
Correct Answer
B. DecreasesExplanation
During an endothermic reaction, temperature decreases because the reaction absorbs heat from the surroundings. This means that the reactants have a higher energy level than the products, causing a decrease in temperature.Rate this question:
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- 28.
During an endothermic reaction, energy is...
- A.
Absorbed
- B.
Released
- C.
Neither absorbed nor released
- D.
Both absorbed and released
Correct Answer
A. AbsorbedExplanation
During an endothermic reaction, energy is absorbed. Endothermic reactions require an input of energy in order to proceed. This means that the reactants have a lower energy level compared to the products, and energy is absorbed from the surroundings to make up for this difference. As a result, the surroundings become cooler, and the reaction is characterized by a decrease in temperature.Rate this question:
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