1.
What characteristic of copper allows it to be made into copper wire?
Correct Answer
D. It is ductile
Explanation
Copper can be made into copper wire because it is ductile. Ductility is the ability of a material to be stretched into a wire without breaking. Copper has high ductility, which means it can be easily drawn into thin wires without losing its structural integrity. This property makes copper an ideal choice for electrical wiring applications, as it can be easily shaped and manipulated into the desired form.
2.
Which pure substance is only composed of one element?
Correct Answer
C. Water
3.
After a chemical reaction occurs in an
open test tube, measurements indicate
that the mass of the reactants is
greater than the mass of the products
remaining in the test tube. What most
likely explains the measurements?
Correct Answer
B. A gas was produced
Explanation
The most likely explanation for the measurements indicating that the mass of the reactants is greater than the mass of the products remaining in the test tube is that a gas was produced during the chemical reaction. Gases have mass, but they are not contained within the test tube, which could result in a decrease in the overall mass of the products.
4.
Which is the best way to determine if
an object is made of pure silver?
Correct Answer
C. Determine the density of the object and compare the known density of pure silver
Explanation
To determine if an object is made of pure silver, the best way is to determine the density of the object and compare it to the known density of pure silver. This is because pure silver has a specific density, so if the object has the same density as pure silver, it is likely made of pure silver. This method is reliable because it is based on a specific property of the material being tested.
5.
Which element is a poor conductor of heat?
Correct Answer
C. Fe
Explanation
Fe (Iron) is a poor conductor of heat because it has a relatively low thermal conductivity compared to other elements. This is due to its atomic structure and the arrangement of its electrons. Iron has a high electrical conductivity, but its thermal conductivity is lower because it does not allow heat to transfer easily through its lattice structure. As a result, Fe is commonly used as a thermal insulator in various applications.
6.
Chemical X has a mass of 5 grams,
and chemical Y has a mass of
10 grams. If the two chemicals are
mixed and a complete chemical
reaction takes place, what is most
likely the mass of the product?
Correct Answer
C. 15 grams
Explanation
When chemical X with a mass of 5 grams and chemical Y with a mass of 10 grams are mixed and undergo a complete chemical reaction, the most likely mass of the product is 15 grams. This is because in a chemical reaction, the total mass of the reactants is conserved and is equal to the total mass of the products. Therefore, the sum of the masses of chemical X and chemical Y (5 grams + 10 grams = 15 grams) is likely to be the mass of the product.
7.
How can a scientist, using the periodic table, find an element with properties similar to another element?
Correct Answer
B. By finding its periodic group
Explanation
A scientist can find an element with properties similar to another element by finding its periodic group. The periodic table is organized into groups or families, which contain elements with similar chemical properties. Elements in the same group have the same number of valence electrons, which determines their reactivity and chemical behavior. Therefore, by identifying the periodic group of an element, a scientist can determine if it shares similar properties with another element in the same group.
8.
Which of the following is an example of a physical change?
Correct Answer
A. Boiling
Explanation
Boiling is an example of a physical change because it involves the change in the state of a substance from a liquid to a gas, without altering its chemical composition. In this process, heat is applied to the substance, causing the molecules to gain energy and move faster, eventually breaking the intermolecular forces and forming a gas. This change is reversible, as the gas can be cooled down to condense back into a liquid state.
9.
Which terms explain how elements combine in different ways to produce compounds?
Correct Answer
D. Ionic and covalent bonding
Explanation
Ionic and covalent bonding are terms that explain how elements combine in different ways to produce compounds. Ionic bonding occurs when one element transfers electrons to another element, resulting in the formation of ions with opposite charges that attract each other. Covalent bonding, on the other hand, occurs when elements share electrons to achieve a stable electron configuration. These two types of bonding are fundamental in understanding the different ways elements can combine and form compounds.
10.
When chemically combined with other elements, what happens to the original element?
Correct Answer
B. It develops a new set of properties
Explanation
When an element is chemically combined with other elements, it undergoes a chemical reaction that leads to the formation of a compound. During this process, the original element loses its original properties and forms a new set of properties in the compound. This is because the atoms of the original element rearrange and bond with atoms of other elements, resulting in the formation of new chemical bonds and a different chemical composition. As a result, the compound formed will have its own unique set of properties that are different from the original element.
11.
If an atom has one electron in its outermost shell, how will the atom most likely combine with other atoms?
Correct Answer
C. By losing electrons
Explanation
When an atom has only one electron in its outermost shell, it is more likely to combine with other atoms by losing electrons. This is because atoms tend to gain or lose electrons in order to achieve a stable electron configuration, typically with a full outer shell. By losing its single outer electron, the atom can achieve a stable configuration and form a bond with another atom that can accept this electron. This process is known as ionization and leads to the formation of positive ions.
12.
Reactant X has a mass of 20 grams. The product of Reactant X and Y has a mass of 50 grams. What is the mass of Reactant Y?
Correct Answer
B. 30 grams
Explanation
Based on the information provided, Reactant X has a mass of 20 grams and the product of Reactant X and Y has a mass of 50 grams. To find the mass of Reactant Y, we subtract the mass of Reactant X from the mass of the product. 50 grams - 20 grams = 30 grams. Therefore, the mass of Reactant Y is 30 grams.
13.
A chemical reaction takes place when one atom of oxygen combines with two atoms of hydrogen. What would be the result of that reaction?
Correct Answer
A. Water is produced
Explanation
When one atom of oxygen combines with two atoms of hydrogen, a chemical reaction occurs resulting in the production of water. This is because the atoms of oxygen and hydrogen bond together to form water molecules, which consist of two hydrogen atoms and one oxygen atom.
14.
If a chemical reaction started with 10 times the amount of oxygen and hydrogen atoms shown, which would support the law of conservation of matter?
2H2 + O2 → 2H2O
Correct Answer
B. There would be 10 times more water produced
Explanation
If a chemical reaction started with 10 times the amount of oxygen and hydrogen atoms shown, there would be 10 times more water produced. This supports the law of conservation of matter because the total number of atoms on both sides of the reaction remains the same. By increasing the amount of reactants, the amount of products also increases proportionally, maintaining the balance of atoms.
15.
Which best supports the law of conservation of matter?
Correct Answer
C. There are the same number of each element on each side of the reaction
Explanation
The law of conservation of matter states that matter cannot be created or destroyed in a chemical reaction, only rearranged. This means that the total number of atoms of each element must be the same on both sides of the reaction. Therefore, the answer "There are the same number of each element on each side of the reaction" supports the law of conservation of matter.
16.
Each element on the periodic table has a different atomic number. What does this number represent?
Correct Answer
A. The number of protons
Explanation
The atomic number represents the number of protons in an atom. Protons are positively charged particles found in the nucleus of an atom. Each element has a unique number of protons, which determines its identity and place on the periodic table. The number of neutrons and half-life are not represented by the atomic number. The chemical symbol is a shorthand representation of an element's name and is not directly related to the atomic number.
17.
The majority of the elements on the periodic table are classified as _____________________
Correct Answer
D. Metals
Explanation
The majority of the elements on the periodic table are classified as metals because they possess certain characteristics such as being good conductors of heat and electricity, having high melting and boiling points, and being malleable and ductile. These properties make metals suitable for various industrial and technological applications. Additionally, metals tend to lose electrons easily, forming positive ions, and are found on the left side of the periodic table.
18.
What is the relationship between elements with 6, 14, and 82 protons in their nuclei on the periodic table of elements?
Correct Answer
A. They are in the same group
Explanation
The elements with 6, 14, and 82 protons in their nuclei are in the same group on the periodic table of elements. This means that they have similar chemical properties and react in similar ways with other elements. The group number indicates the number of valence electrons, which determines the element's reactivity and bonding behavior. Therefore, elements in the same group have similar characteristics and tend to exhibit similar chemical behavior.
19.
If a highly reactive metal with 1 valence electron is discovered, in which group would the element best fit?
Correct Answer
A. Group 1
Explanation
A highly reactive metal with 1 valence electron would best fit in Group 1. Group 1 elements, also known as alkali metals, have 1 valence electron and are highly reactive due to their low ionization energy. These metals readily lose their valence electron to form a positive ion, making them highly reactive with other elements. Therefore, a highly reactive metal with 1 valence electron would belong to Group 1.
20.
An unknown element is being studied in a lab. The element is nonreactive, but only has two valence electrons. Which element is being studied?
Correct Answer
C. Helium (He)
Explanation
Helium is the correct answer because it is a nonreactive element with two valence electrons. Helium is located in the noble gas group on the periodic table, which means it has a full outer electron shell and is stable. This stability is why helium does not readily react with other elements. Neon, oxygen, and hydrogen all have different numbers of valence electrons and therefore do not fit the description given in the question.
21.
Understanding Element Organization
5 Atomic #
B Chemical Symbol
10.81 Atomic Mass
Using the information above, answer the following question. Which element is shown?
Correct Answer
A. Boron
Explanation
The information provided in the table includes the atomic number, chemical symbol, and atomic mass of an element. The chemical symbol "B" corresponds to the element Boron, which has an atomic number of 5 and an atomic mass of 10.81. Therefore, the correct answer is Boron.
22.
Understanding Element Organization
5 Atomic #
B Chemical Symbol
10.81 Atomic Mass
Using the information above, answer the following question. What is the relationship between the atomic # and the # of protons?
Correct Answer
B. The two numbers are the same
Explanation
The atomic number of an element represents the number of protons in the nucleus of an atom. Therefore, the relationship between the atomic number and the number of protons is that they are the same.
23.
Based on the periodic table, which best describes the characteristics of an element located at the far right of the table?
Correct Answer
B. Gas, and a poor conductor of heat and electricity
Explanation
The element located at the far right of the periodic table is a gas, as most of the elements in that region are gases. Additionally, it is a poor conductor of heat and electricity. This is because elements on the right side of the periodic table tend to have high ionization energies and electronegativities, which make it difficult for them to conduct heat and electricity effectively.
24.
Which description would be evidence that a chemical change has taken place?
Correct Answer
C. Gas bubbles form when a substance is put into water.
Explanation
Gas bubbles form when a substance is put into water is evidence that a chemical change has taken place. This is because the formation of gas bubbles indicates the release of a gas, which is a characteristic of a chemical reaction. The interaction between the substance and water has caused a chemical reaction to occur, resulting in the formation of gas bubbles.
25.
Which element has 7 valence electrons?
Correct Answer
D. Flourine
Explanation
Fluorine has 7 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom that are involved in chemical reactions. Fluorine is in Group 17 of the periodic table, which means it has 7 electrons in its outermost energy level.
26.
A solid formed in a chemical reaction is called a(n)
Correct Answer
B. Precipitate
Explanation
A solid formed in a chemical reaction is called a precipitate. This occurs when two or more substances react and produce an insoluble solid that separates from the solution. The formation of a precipitate is a common occurrence in many chemical reactions, especially those involving ionic compounds. The solid precipitate can be easily separated from the solution through filtration or decantation.
27.
Which of the following is not a type of chemical bond?
Correct Answer
B. Precipitate
Explanation
A precipitate is not a type of chemical bond. It refers to a solid that forms when two aqueous solutions react chemically with each other, resulting in the formation of an insoluble product. In contrast, ionic, metallic, and covalent bonds are all types of chemical bonds that involve the sharing or transfer of electrons between atoms.
28.
A type of reaction in which there is a temperature change and the substance gets hot is known as a(n) _______________
Correct Answer
D. Exothermic
Explanation
An exothermic reaction is a type of reaction in which there is a temperature change and the substance gets hot. In an exothermic reaction, energy is released in the form of heat. This is the opposite of an endothermic reaction, where energy is absorbed from the surroundings, causing the substance to become cooler. Ionic and covalent refer to the types of chemical bonds, and do not necessarily indicate whether a reaction is exothermic or endothermic.
29.
Ions, charged particles, are formed as a result of which type of bond?
Correct Answer
C. Ionic
Explanation
Ions, which are charged particles, are formed as a result of an ionic bond. In an ionic bond, one atom transfers electrons to another atom, creating positive and negative ions. This transfer of electrons leads to the formation of a strong electrostatic attraction between the oppositely charged ions, creating a stable bond. This is different from covalent bonds, where atoms share electrons, and metallic bonds, where electrons are delocalized among a sea of atoms.
30.
Which type of bond gives metal the ability to be flexible, malleable, and ductile?
Correct Answer
C. Metallic
Explanation
Metallic bonds give metals the ability to be flexible, malleable, and ductile. In metallic bonding, the valence electrons are delocalized and free to move throughout the metal lattice, creating a "sea" of electrons. This allows the metal atoms to slide past each other easily, making the metal flexible. The delocalized electrons also contribute to the metal's ability to conduct electricity and heat. Additionally, the delocalized electrons give the metal its malleability and ductility, as they can be easily rearranged without breaking the bond between the metal atoms.
31.
Please balance the following. Your answer choices will put the coefficients in the order that they appear in the equation.
Zn + HCl ---> ZnCl2 + H2
Correct Answer
B. 1Zn + 2HCl ---> 1ZnCl2 + 1H2
Explanation
The balanced equation for the reaction between zinc (Zn) and hydrochloric acid (HCl) is 1Zn + 2HCl ---> 1ZnCl2 + 1H2. This equation is balanced because it has an equal number of atoms of each element on both sides of the equation. There is 1 zinc atom (Zn) and 2 hydrogen atoms (H) on the left side, and 1 zinc chloride molecule (ZnCl2) and 1 hydrogen molecule (H2) on the right side. Therefore, this equation represents the correct stoichiometry of the reaction.
32.
Please balance the following. Your answer choices will put the coefficients in the order that they appear in the equation.
C5H12 + O2 ---> CO2 + H2O
Correct Answer
C. 1C5H12 + 8O2 ---> 5CO2 + 6H2O
Explanation
The balanced equation shows that for every 1 molecule of C5H12, 8 molecules of O2 are required to produce 5 molecules of CO2 and 6 molecules of H2O. This is determined by the stoichiometric coefficients in the balanced equation. The other answer choices do not have the correct ratio of reactants and products, therefore they are not balanced.
33.
What type of reaction is showed in the following example:
Zn + HCl ---> ZnCl2 + H2
Correct Answer
C. Single Displacement
Explanation
The reaction shown in the example is a single displacement reaction. In this type of reaction, one element replaces another element in a compound. In the given reaction, zinc (Zn) displaces hydrogen (H) in hydrochloric acid (HCl) to form zinc chloride (ZnCl2) and hydrogen gas (H2). This is indicated by the change in the chemical equation, where Zn replaces H in the compound.
34.
What type of reaction is shown in the following example:
FeCl3 + NH4OH ---> Fe(OH)3 + NH4Cl
Correct Answer
D. Double Displacement
Explanation
The reaction shown in the example is a double displacement reaction. In this type of reaction, the cations and anions of two different compounds switch places, forming two new compounds. In this case, FeCl3 and NH4OH react to form Fe(OH)3 and NH4Cl. The Fe3+ ion from FeCl3 combines with the OH- ion from NH4OH to form Fe(OH)3, while the NH4+ ion from NH4OH combines with the Cl- ion from FeCl3 to form NH4Cl.
35.
What type of reaction is shown in the following example:
H2CO3--->H2O + CO2
Correct Answer
B. Decomposition
Explanation
The reaction shown in the example is a decomposition reaction. In this type of reaction, a compound breaks down into simpler substances. In the given equation, H2CO3 (carbonic acid) decomposes into H2O (water) and CO2 (carbon dioxide).
36.
What type of reaction is shown in the following example:
2Na + Cl2 ----> 2NaCl
Correct Answer
A. Synthesis
Explanation
The given chemical equation represents a synthesis reaction. In a synthesis reaction, two or more substances combine to form a single compound. In this case, sodium (Na) reacts with chlorine (Cl2) to produce sodium chloride (NaCl). The reactants combine to form a new compound, which is the product.