Physical Science Module 4

1.

The use of electricity to break a molecule down into smaller units refers to:

A.

Electrodes
B.

Experimental error
C.

Electrolysis
D.

Cold Fusion

Correct Answer
C. Electrolysis

Explanation
Electrolysis is the process of using electricity to break a molecule down into smaller units. It involves the use of electrodes to conduct the electric current through an electrolyte solution, causing the chemical reaction to occur. This process is commonly used in various industries, such as metal extraction, electroplating, and water splitting. Cold Fusion is not relevant to this concept, and experimental error refers to mistakes or deviations in the experimental procedure that may affect the results. Therefore, the correct answer is Electrolysis.

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2.

A molecule that has slight positive and negative charges due to an imbalance in the way electrons are shared refers to a:

A.

Polarity
B.

Polar Molecule
C.

Nonpolar Molecule

Correct Answer
B. Polar Molecule

Explanation
A molecule that has slight positive and negative charges due to an imbalance in the way electrons are shared refers to a polar molecule. In a polar molecule, the electrons are not shared equally between the atoms, resulting in a partial positive charge on one end of the molecule and a partial negative charge on the other end. This imbalance in charge distribution creates a polarity within the molecule.

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3.

A liquid substance capable of dissolving other substances refers to a:

A.

Solvent
B.

Solute
C.

Solution
D.

Compound

Correct Answer
A. Solvent

Explanation
A liquid substance capable of dissolving other substances refers to a solvent. Solvents are substances that have the ability to dissolve other substances, known as solutes, to form a solution. Solvents are commonly used in various industries and everyday life, such as in cleaning products, paints, and pharmaceuticals. They are often polar or nonpolar in nature, depending on the type of solute they are intended to dissolve.

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4.

A substance that is dissolved in a solvent is a:

A.

Compound
B.

Solution
C.

Molecule
D.

Solute

Correct Answer
D. Solute

Explanation
A substance that is dissolved in a solvent is referred to as a solute. In a solution, the solute is the component that is present in a smaller quantity and gets dissolved in the solvent. It can be a solid, liquid, or gas that is evenly distributed throughout the solvent. In this case, the correct answer is "Solute" as it accurately describes the substance being dissolved in a solvent.

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5.

The phenomenon that occurs when individual molecules are so strongly attracted to each other that they tend to stay together, even when exposed to tension refers to:

A.

Magnetism
B.

Elasticity
C.

Cohesion
D.

Polar Bonding

Correct Answer
C. Cohesion

Explanation
Cohesion refers to the phenomenon where individual molecules are strongly attracted to each other, causing them to stay together even when exposed to tension. This attraction is typically due to intermolecular forces such as hydrogen bonding or van der Waals forces. Cohesion is responsible for the surface tension of liquids and the ability of water to form droplets. Magnetism refers to the attraction or repulsion between objects due to the presence of magnetic fields. Elasticity refers to the ability of a material to regain its original shape after being stretched or compressed. Polar bonding refers to the sharing of electrons between atoms with different electronegativities, resulting in a partial positive and partial negative charge on the atoms involved.

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6.

Water that has certain dissolved ions in it -- predominately calcium and magnesium ions refers to:

A.

Hard Water
B.

Sulfur Water
C.

Soft Water
D.

Chlorinated Water

Correct Answer
A. Hard Water

Explanation
Hard water refers to water that has a high concentration of dissolved ions, particularly calcium and magnesium ions. These ions can cause mineral deposits to form on surfaces and can make it difficult for soap to lather. This is in contrast to soft water, which has a low concentration of these ions. Hard water is a common issue in many areas and can have negative effects on plumbing systems and appliances.

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7.

The chemical formula for water is H2O.

A.

True
B.

False

Correct Answer
A. True

Explanation
The chemical formula for water is H2O because it consists of two hydrogen atoms (H) bonded to one oxygen atom (O). This formula represents the ratio of atoms in a water molecule, where each molecule contains two hydrogen atoms and one oxygen atom.

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8.

Some metals tend to absorb oxygen but not hydrogen. Suppose such a metal was covering the battery in an electrolysis experiment like Experiment 4.1. Which is the more likely erroneous result the experiment would yield for the chemical formula of water: HO2 or H4O?

A.
B.

Correct Answer
B.

Explanation
The more likely erroneous result the experiment would yield for the chemical formula of water is H4O. This is because the metal tends to absorb oxygen, so it is more likely that the metal would combine with multiple hydrogen atoms (H4) rather than with multiple oxygen atoms (O2).

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9.

What is the reason that water is a liquid at room temperature when all other chemically similar substances are gases at room temperature?

A.

Chemical Bonding
B.

Heat Bonding
C.

Hydrogen Bonding

Correct Answer
C. Hydrogen Bonding

Explanation
Water is a liquid at room temperature due to the presence of hydrogen bonding. Hydrogen bonding occurs when the positively charged hydrogen atom in one water molecule is attracted to the negatively charged oxygen atom in another water molecule. This bonding is stronger than the intermolecular forces present in other chemically similar substances, such as hydrogen sulfide or ammonia, which causes them to be gases at room temperature. The hydrogen bonding in water allows it to have a higher boiling point and remain a liquid at normal temperatures.

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10.

Carbon dioxide (CO2) is one of the gases that we exhale when we breathe. Carbon monoxide (CO) is a poisonous gas associated with burning under conditions of low oxygen. How many atoms are in one molecule of CO2? How many atoms are in one molecule of CO?

A.

has 2 atoms and CO has 1 atom
B.

has 3 atoms and CO has 2 atoms
C.

has 4 atoms and CO has 2 atoms

Correct Answer
B. has 3 atoms and CO has 2 atoms

Explanation
Carbon dioxide (CO2) is composed of one carbon atom and two oxygen atoms, totaling three atoms in one molecule. On the other hand, carbon monoxide (CO) consists of one carbon atom and one oxygen atom, resulting in two atoms in one molecule.

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11.

An important component of gasoline is octane, which is composed of molecules that have eight carbon atoms (C) and eighteen hydrogen atoms (H). What is the chemical formula of octane?

A.
B.
C.

Correct Answer
C.

Explanation
The chemical formula of octane is C8H18.

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0

1

12.

Water molecules are ____________ because both the oxygen atoms (which make it slightly negative) and the hydrogen atoms (which make it slightly positive) are fighting over the electrons they are supposed to be sharing.

A.

Bipolar
B.

Polar
C.

Nonpolar

Correct Answer
B. Polar

Explanation
Water molecules are polar because the oxygen atom pulls the shared electrons towards itself more strongly than the hydrogen atoms, creating a slight negative charge near the oxygen atom and a slight positive charge near the hydrogen atoms. This unequal distribution of charge creates a dipole moment, making water a polar molecule.

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13.

If a substance does not dissolve in water, it is most likely:

A.

Ionic
B.

Polar
C.

Nonpolar

Correct Answer
C. Nonpolar

Explanation
If a substance does not dissolve in water, it is most likely nonpolar. This is because water is a polar molecule, meaning it has a partial positive charge on one end and a partial negative charge on the other. Nonpolar substances, on the other hand, do not have a charge separation and are not attracted to the polar water molecules. Therefore, they do not dissolve in water.

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14.

Hard water is the result of:

A.

Calcium-containing compounds in the region from which the water is taken.
B.

A city's water treatment process.
C.

The crystallization process which occurs at 32 F at sea level.

Correct Answer
A. Calcium-containing compounds in the region from which the water is taken.

Explanation
Hard water is caused by the presence of calcium-containing compounds in the region from which the water is sourced. These compounds, such as calcium carbonate, dissolve in the water and form mineral deposits. When the water is heated or evaporates, these minerals are left behind, causing scale buildup on surfaces and reducing the effectiveness of soaps and detergents. The city's water treatment process and the crystallization process at 32F at sea level are not directly related to the formation of hard water.

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15.

If a substance dissolves in water, it will also dissolve in vegetable oil, a nonpolar substance.

A.

True
B.

False

Correct Answer
B. False

Explanation
This statement is false because substances that dissolve in water, which is a polar substance, do not necessarily dissolve in vegetable oil, a nonpolar substance. The solubility of a substance depends on its polarity. Polar substances dissolve in polar solvents, while nonpolar substances dissolve in nonpolar solvents. Therefore, a substance that dissolves in water may not dissolve in vegetable oil.

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