Question 1

When a substance dissolves, heat is added to the compound in the solid state, and it is converted to the liquid state.When a substance melts, as in water, the substance becomes surrounded by solvent molecules, and no heat is added.

Accepted Answer

When a substance melts, heat is added to the substance to break the intermolecular forces holding the molecules together in the solid state. As the substance becomes surrounded by solvent molecules, heat is released, causing the temperature to remain constant until all of the solid has melted. Therefore, the statement in the question is false.

Question 2

Methane, CH₄, and acetic acid, CH₃CO₂H, are both acids because they both contain hydrogen.

Accepted Answer

Methane and acetic acid both contain hydrogen atoms that can act as donors in acid-base reactions, making them both acids.

Question 3

A molecular compound is composed of atoms of a metal and a nonmetal.

Accepted Answer

A molecular compound is actually composed of atoms of two or more nonmetals. A compound composed of a metal and a nonmetal is usually an ionic compound.

Question 4

When naming binary molecular compounds, it is always unnecessary to use Greek prefixes.

Accepted Answer

Binary molecular compounds consist of two nonmetal atoms that combine through covalent bonding. In order to indicate the number of atoms of each element in the compound, Greek prefixes are used to indicate the number of each type of atom. For example, carbon dioxide (CO2) uses the prefix "di-" to indicate that there are two oxygen atoms.

Question 5

The central atom is normally listed first in the formula for a binary molecule or ion.

Accepted Answer

The central atom is usually listed first when writing the formula for a binary molecule or ion. This is because it is usually the more electronegative or the one with the higher oxidation state, and therefore has a greater influence on the properties of the molecule or ion.

Question 6

Nonelectrolytes are compounds which break apart into ions when dissolved in water.

Accepted Answer

Nonelectrolytes are compounds that do not break apart into ions when dissolved in water.

Question 7

In the old system of naming ionic compounds formed from metals with two different charges, the suffix -ous is used for the higher charge, while the suffix -ic indicates the lower charge.

Accepted Answer

In the old system of naming ionic compounds formed from metals with two different charges, the suffix -ous is used for the lower charge, while the suffix -ic indicates the higher charge.

Question 8

This image shows the process of melting sodium chloride.

Accepted Answer

The answer of This image shows the process of melting...

Question 9

Most molecular compounds remain as molecules when dissolved in water.

Accepted Answer

Most molecular compounds do not ionize in water and remain as intact molecules when dissolved, such as sugar, ethanol, and methane. Exceptions include polar covalent compounds, such as acids and bases, which can ionize in water.

Question 10

Water has H at the beginning of its formula, so it is considered to be an acid.

Accepted Answer

This statement is false. Water (H2O) is actually considered to be neutral, not an acid or a base. The acidity or basicity of a substance is determined by the concentration of hydrogen ions (H+) and hydroxide ions (OH-) in the solution, and in pure water these concentrations are equal, resulting in a neutral pH of 7.

Question 11

Polyatomic ions that contain oxygen attached to some other element are called oxoanions.

Accepted Answer

The statement is correct. Polyatomic ions containing oxygen along with other elements are known as oxoanions. Examples include sulfate (SO4²⁻), nitrate (NO3⁻), and phosphate (PO4³⁻) ions.

Question 12

From their position in the periodic table, we would predict that both oxygen and sulfur would have a charge of 2^-in a binary ionic compound.

Accepted Answer

Oxygen and sulfur are in the same group (Group 16) of the periodic table, and they typically gain two electrons to achieve a stable octet, resulting in a 2- charge in binary ionic compounds.

Quiz 3: Chemical Compounds