1.
What is the name of Li2S?
Correct Answer
A. Lithium sulfide
Explanation
Lithium sulfide is the correct answer because Li2S is the chemical formula for this compound. It consists of two lithium atoms bonded to one sulfur atom. The name "lithium sulfide" accurately represents the composition of the compound and follows the naming conventions for binary ionic compounds. The other options, dilithium sulfide and lithium (II) sulfide, do not correctly represent the composition of Li2S. Lithium sulfate, on the other hand, is a different compound with the chemical formula Li2SO4.
2.
What is the name of Pb(SO4)2?
Correct Answer
D. Lead (IV) sulfate
Explanation
Lead (IV) sulfate is the correct answer because the compound Pb(SO4)2 contains lead (Pb) in its highest oxidation state, which is +4. The sulfate ion (SO4) has a charge of -2, so in order to balance the charges, two sulfate ions are needed for every one lead ion. Therefore, the correct name for this compound is Lead (IV) sulfate.
3.
What type of reaction is
H2O2 ----> H2 + O2
Correct Answer
B. Decomposition
Explanation
The given reaction involves a single reactant, H2O2, which breaks down into two products, H2 and O2. This type of reaction, where a compound breaks down into simpler substances, is known as decomposition.
4.
Which numbers would balance the equation below?
__ H2O à__ H2 + __ O2
Correct Answer
D. 2, 2, 1
5.
What type of reaction is
PbO + HCl----> H2O + PbCl2
Correct Answer
D. Double Replacement
Explanation
In the given reaction, PbO reacts with HCl to form H2O and PbCl2. This is a double replacement reaction because the cations (Pb2+ and H+) from the reactants switch places to form new compounds (H2O and PbCl2). Double replacement reactions involve the exchange of ions between two compounds.
6.
Which numbers would balance the equation below?
____ HBr + ____ Mg(OH)2 → ____ MgBr2 + ____ H2O
Correct Answer
B. 2, 1, 1, 2
Explanation
The equation represents a chemical reaction between hydrobromic acid (HBr) and magnesium hydroxide (Mg(OH)2) to form magnesium bromide (MgBr2) and water (H2O). To balance the equation, the number of atoms of each element on both sides of the equation must be equal. By assigning the numbers 2, 1, 1, and 2 to HBr, Mg(OH)2, MgBr2, and H2O respectively, the equation is balanced.
7.
What is the name of P2O3?
Correct Answer
D. DipHospHorus trioxide
Explanation
The correct answer is Diphosphorus trioxide because P2O3 is a compound made up of two phosphorus atoms and three oxygen atoms. The prefix "di-" indicates that there are two phosphorus atoms present, and the term "tri-" indicates that there are three oxygen atoms present. Therefore, the name "Diphosphorus trioxide" accurately describes the composition of the compound.
8.
What type of reaction is
AgNO3 + Li → LiNO3 + Ag
Correct Answer
C. Single Replacement
Explanation
In the given reaction, AgNO3 reacts with Li to form LiNO3 and Ag. This is a single replacement reaction because one element (Li) replaces another element (Ag) in the compound (AgNO3).
9.
Which numbers would balance the equation below?
____ CoBr3 + ____ CaSO4 → ____ CaBr2 + ____ Co2(SO4)3
Correct Answer
C. 2, 3, 3, 1
10.
What is the name of (NH4)2CO3?
Correct Answer
A. Ammonium carbonate
Explanation
Ammonium carbonate is the correct answer because (NH4)2CO3 is a compound formed by the combination of the ammonium ion (NH4+) and the carbonate ion (CO3^2-). The compound is commonly known as ammonium carbonate and is used in various applications such as baking, as a smelling salt, and in the manufacturing of dyes and pigments. The other options, diammonium carbonate, ammonium (II) carbonate, and ammonium carbontrioxide, do not accurately represent the chemical formula or common name of (NH4)2CO3.
11.
What type of reaction is
P4 + Br2 → PBr3
Correct Answer
A. Synthesis
Explanation
The reaction P4 + Br2 → PBr3 is a synthesis reaction. In a synthesis reaction, two or more substances combine to form a single product. In this case, phosphorus (P4) reacts with bromine (Br2) to produce phosphorus tribromide (PBr3).
12.
What is the name of H2S (aq)?
Correct Answer
C. Hydrosulfuric acid
Explanation
Hydrosulfuric acid is the correct answer because H2S (aq) is the chemical formula for hydrosulfuric acid. It is a weak acid that is formed when hydrogen sulfide gas dissolves in water. It is commonly used in various industrial processes and has a distinct odor of rotten eggs. Sulfide acid, sulfur acid, and sulfuric acid are incorrect answers as they do not correspond to the correct chemical formula for H2S (aq).
13.
Which numbers would balance the equation below?
NaCN + ____ CuCO3 → ____ Na2CO3 + ____ Cu(CN)2
Correct Answer
D. 2, 1, 1, 1
Explanation
The equation is balanced when there are equal numbers of each type of atom on both sides of the equation. In this case, there are 2 sodium (Na) atoms on the left side, so there must be 2 sodium atoms on the right side. There is 1 copper (Cu) atom on the left side, so there must be 1 copper atom on the right side. There is 1 carbon (C) atom on the left side, so there must be 1 carbon atom on the right side. Finally, there is 1 nitrogen (N) atom on the left side, so there must be 1 nitrogen atom on the right side. Therefore, the numbers that balance the equation are 2, 1, 1, 1.
14.
What do all acids have in common?
Correct Answer
B. They will donate H+ ions to an aqueous solution
Explanation
All acids have the common characteristic of donating H+ ions to an aqueous solution. This is what defines an acid and allows it to exhibit its acidic properties. Acids are known to increase the concentration of H+ ions in a solution, which leads to the characteristic sour taste, ability to conduct electricity, and reaction with bases to form salts and water. The other options provided in the question, such as burning the skin or donating OH- ions, are not true for all acids and do not define acids in general.
15.
What will be the products of the double replacement reaction below?
HCl + AgCN →
Correct Answer
C. HCN + AgCl
Explanation
In a double replacement reaction, the positive and negative ions in the reactants switch places to form new compounds. In this reaction, the chloride ion (Cl-) from hydrochloric acid (HCl) will combine with the silver ion (Ag+) from silver cyanide (AgCN) to form silver chloride (AgCl). The remaining ions, hydrogen (H+) and cyanide (CN-), will combine to form hydrogen cyanide (HCN). Therefore, the products of the reaction will be HCN and AgCl.
16.
Which of the following is always a reactant in a combustion reaction
Correct Answer
D. Oxygen
Explanation
In a combustion reaction, oxygen is always a reactant because it is required for the process of combustion to occur. Combustion is a chemical reaction that involves the rapid combination of a fuel (such as hydrocarbons) with oxygen to produce heat, light, and usually carbon dioxide and water as byproducts. Without oxygen, combustion cannot take place. Therefore, oxygen is always present as a reactant in a combustion reaction.
17.
Which of the following pairs will form a molecular bond?
Correct Answer
A. Carbon and Oxygen
Explanation
Carbon and Oxygen will form a molecular bond because they are both nonmetals and have a difference in electronegativity. Carbon has four valence electrons and Oxygen has six valence electrons. Carbon can share two electrons with Oxygen to form a double bond, creating a stable molecule called carbon dioxide (CO2). This sharing of electrons allows both atoms to achieve a full outer electron shell, resulting in a strong molecular bond between them.
18.
Which of the following pairs will form an ionic compound?
Correct Answer
B. Magnesium and fluorine
Explanation
Magnesium and fluorine will form an ionic compound because magnesium has a low electronegativity and tends to lose electrons, while fluorine has a high electronegativity and tends to gain electrons. This creates a transfer of electrons from magnesium to fluorine, resulting in the formation of an ionic bond.
19.
When writing a chemical equation, a catalyst can be placed above the arrow because
Correct Answer
D. It is not changed from its original form when the reaction is complete
Explanation
A catalyst can be placed above the arrow in a chemical equation because it is not changed from its original form when the reaction is complete. Unlike reactants and products, which are consumed or formed during the reaction, a catalyst remains unchanged and can be reused in subsequent reactions. It facilitates the reaction by providing an alternative pathway with lower activation energy, but it is not consumed in the process. Therefore, it is represented separately above the arrow to indicate its role in the reaction without being incorporated into the overall equation.
20.
Which of the following is a polyatomic ion?
Correct Answer
A. CN-
Explanation
The correct answer is CN-. A polyatomic ion is a charged species that consists of two or more atoms bonded together. In this case, CN- is a polyatomic ion because it consists of a carbon atom bonded to a nitrogen atom, with an overall charge of -1. Mg2+, Pb4+, and Se2- are not polyatomic ions as they consist of only one atom with a charge.
21.
What is the name of MgF2?
Correct Answer
D. Magnesium fluoride
Explanation
The correct answer is "Magnesium fluoride". This is the correct name for the compound MgF2 according to the naming conventions for binary compounds. The name indicates that the compound consists of one magnesium atom bonded to two fluorine atoms.