1.
Elements that lie on the left side of the periodic table are generally non-metals.
Correct Answer
B. False
Explanation
Elements that lie on the left side of the periodic table are generally metals, not non-metals. The left side of the periodic table is known as the "s-block" and it includes the alkali metals and alkaline earth metals, which are all metals. Non-metals are typically found on the right side of the periodic table, in the "p-block". Therefore, the statement that elements on the left side of the periodic table are generally non-metals is incorrect.
2.
Light from a glow stick is a sign of a chemical change?
Correct Answer
A. True
Explanation
The light from a glow stick is a sign of a chemical change because it is produced by a chemical reaction. Glow sticks contain two separate compartments, one containing a hydrogen peroxide solution and the other containing a fluorescent dye. When the stick is bent, the compartments mix, causing the chemicals to react. This reaction produces light through a process called chemiluminescence, where energy is released in the form of light. Therefore, the light emitted from a glow stick is a result of a chemical change.
3.
Ionic bonds are formed when oppositely charged molecules are attracted to one another.
Correct Answer
B. False
Explanation
Ionic bonds are not formed between molecules, but rather between atoms. An ionic bond occurs when one atom donates one or more electrons to another atom, leading to the formation of ions. These ions, which carry opposite charges (one being positively charged and the other negatively charged), are then attracted to each other, creating the ionic bond. This kind of bonding typically occurs between metals and nonmetals, where the metal loses electrons to become a positively charged cation and the nonmetal gains those electrons to become a negatively charged anion. Thus, the statement should refer to atoms or ions rather than molecules.
4.
In an anion, the number of protons is equal to the number of electrons?
Correct Answer
B. False
Explanation
False. In an anion, the number of electrons is greater than the number of protons, resulting in a negative charge. Anions are formed when an atom gains electrons during chemical reactions. Neutral atoms have the same number of protons as electrons.
5.
A supplier label for a hazardous chemical is required by law to have a hatched border.
Correct Answer
B. False
Explanation
The requirement for a hatched border on supplier labels for hazardous chemicals was part of the older WHMIS (Workplace Hazardous Materials Information System) 1988 regulations. However, under the updated WHMIS 2015 regulations, the hatched border is no longer required. The new regulations are aligned with the Globally Harmonized System (GHS) of Classification and Labelling of Chemicals, which does not mandate the hatched border .
6.
The mass number of an atom is the sum of its protons and neutrons?
Correct Answer
A. True
Explanation
The mass number of an atom is the sum of its protons and neutrons. This is because protons and neutrons contribute to the mass of an atom, while electrons have negligible mass. Therefore, adding the number of protons and neutrons gives us the mass number of an atom.
7.
Nitrous oxide, N2O, is an example of an ionic compound.
Correct Answer
B. False
Explanation
Nitrous oxide, N2O, is not an ionic compound. It is a covalent compound because it is composed of two nonmetals, nitrogen and oxygen, which share electrons to form bonds. Ionic compounds are often formed between a metal and a nonmetal, where electrons are transferred from the metal to the nonmetal to form ions. Since N2O does not fit this criteria, it is not an ionic compound.
8.
Which observation provides information about the chemical properties of a substance?
Correct Answer
C. The substance burns brightly in the air
Explanation
The observation that the substance burns brightly in the air provides information about its chemical properties. This suggests that the substance is likely flammable and reacts with oxygen in the air to produce a bright flame. This observation indicates that the substance has the potential to undergo a chemical reaction, specifically combustion, which is a characteristic of certain chemical compounds.
9.
Which element would have atoms with the same number of outer electrons as carbon atoms?
Correct Answer
A. Silicon
Explanation
Silicon would have atoms with the same number of outer electrons as carbon atoms. Both carbon and silicon belong to Group 14 of the periodic table, which means they have 4 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom, and they determine the chemical properties of an element. Since both carbon and silicon have 4 valence electrons, they have the same number of outer electrons.
10.
Which would be composed of molecules?
Correct Answer
D. Both B and C
Explanation
Sodium citrate is a compound consisting of sodium ions and citrate ions. While the sodium ions are not part of molecules, the citrate ion itself is a molecular ion composed of carbon, hydrogen, and oxygen atoms covalently bonded. The entire sodium citrate compound in its typical usage in chemistry is often considered a molecular entity due to the presence of the citrate molecule. Methane is a clear example of a molecular compound. It is composed of one carbon atom and four hydrogen atoms covalently bonded together, forming a molecule. Solid sodium citrate and CH4​ gas (methane) are composed of molecules, with methane being the most straightforward example of a molecular compound. Sodium citrate, though ionic in part, includes a citrate ion which behaves as a molecular ion.
11.
Of the following, which would be the best conductor of electricity?
Correct Answer
C. Seawater
Explanation
Seawater would be the best conductor of electricity among the given options. This is because seawater contains a higher concentration of dissolved salts and minerals compared to pure water, tap water, or freshwater from a lake. These dissolved ions, such as sodium and chloride, act as conductors of electricity, allowing the flow of electric current more easily through seawater than through the other options.
12.
What is the correct chemical formula for the compound aluminum chloride?
Correct Answer
B. AlCl3
Explanation
The correct chemical formula for the compound aluminum chloride is AlCl3. In this compound, aluminum has a +3 charge and chlorine has a -1 charge. To balance the charges, three chlorine atoms are needed for every one aluminum atom, resulting in the formula AlCl3.
13.
What is the correct chemical formula for the compound copper (II) fluoride?
Correct Answer
A. CuF2
Explanation
The correct chemical formula for the compound copper (II) fluoride is CuF2. In this compound, copper has a charge of +2 (as indicated by the Roman numeral II in parentheses) and fluoride has a charge of -1. To balance the charges, two fluoride ions are needed for every copper ion, resulting in the formula CuF2.
14.
What is the correct name for the compound K2O?
Correct Answer
D. Potassium Oxide
Explanation
The correct name for the compound K2O is Potassium Oxide. This is because the compound consists of two potassium atoms (K2) and one oxygen atom (O), resulting in the formula K2O. According to the rules of chemical nomenclature, the name of the compound is derived from the names of its constituent elements, with the metal (potassium) coming first followed by the non-metal (oxygen) with the suffix "-ide". Therefore, Potassium Oxide is the appropriate name for the compound K2O.