Question 1

The temperature of evaporation is much higher for water than for alcohol. Without knowing more about the chemistry of alcohol, which of the following is the most logical chemical explanation for this phenomenon?

Accepted Answer

The higher temperature of evaporation for water compared to alcohol can be attributed to the fact that water molecules form stronger hydrogen bonds with neighboring water molecules than alcohol molecules do with each other. This means that more energy (heat) is required to break the intermolecular bonds between water molecules and allow them to enter the gas phase. As fewer hydrogen bonds form between alcohol molecules, less heat is needed for alcohol molecules to break away from solution and enter the air, resulting in a lower temperature of evaporation. Therefore, option D is the most logical chemical explanation for this phenomenon.

Question 2

Which of the following statements regarding the oxygen atom of a water molecule is true?

Accepted Answer

Oxygen is more electronegative than the hydrogen atoms, meaning it has a greater attraction for shared electrons in chemical bonds. This makes the oxygen atom slightly negatively charged and the hydrogen atoms slightly positively charged in a water molecule.

Question 3

As ice melts

Accepted Answer

When ice melts, hydrogen bonds between water molecules are broken, allowing them to move more freely.

Question 4

Water molecules stick to other water molecules because

Accepted Answer

Water molecules stick together due to hydrogen bonding, which occurs between the slightly positively charged hydrogen atoms of one water molecule and the slightly negatively charged oxygen atoms of another water molecule. This creates a cohesive force that allows water molecules to form surface tension and stick together in a mass, such as in a droplet or a body of water.

Question 5

Which of the following statements regarding chemical reactions is false?

Accepted Answer

Chemical reactions involve the redistribution of electrons, but they do not create or destroy them. The overall number of electrons remains constant in chemical reactions due to the law of conservation of mass.

Question 6

Table salt is formed when

Accepted Answer

Sodium has one outer electron, while chlorine has seven. In order to fill their outermost shells, sodium donates its single outer electron to chlorine, forming an ionic bond and resulting in the formation of table salt (NaCl).

Question 7

Which of the following statements about water is false?

Accepted Answer

Ice is less dense than liquid water, which is why it floats on top of it.

Question 8

The tendency of water molecules to stick together is referred to as

Accepted Answer

The tendency of water molecules to stick together is called cohesion. Adhesion refers to the tendency of water molecules to stick to other substances. Polarity refers to the distribution of electric charge within a molecule, and transpiration refers to the process by which plants release water vapor into the atmosphere.

Question 9

A(n) ________ forms when two atoms share electrons.

Accepted Answer

Covalent bonds form when two atoms share electrons to achieve a stable octet configuration. Ionic bonds involve the transfer of electrons from one atom to another, while hydrogen bonds involve an attraction between the partial positive charge of a hydrogen atom and the partial negative charge of another atom. Ions are formed when an atom gains or loses electrons, resulting in a net positive or negative charge. Therefore, the best choice for this question is B) covalent bond.

Question 10

In a water molecule, hydrogen and oxygen are held together by a ________ bond.

Accepted Answer

In a water molecule, the hydrogen and oxygen atoms are held together by a polar covalent bond. The electrons in the bond are shared unequally between the atoms, with oxygen pulling the electrons closer to itself due to its higher electronegativity. This creates a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms, making water a polar molecule.

Question 11

A single water molecule (H-O-H) is held together by

Accepted Answer

A water molecule contains two polar covalent bonds between the oxygen atom and each of the hydrogen atoms.

Question 12

A hydrogen atom has one electron. How many covalent bonds can hydrogen form?

Accepted Answer

Hydrogen can form only one covalent bond because it has only one valence electron to share with another element.

Question 13

________ are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.

Accepted Answer

Hydrogen bonds are weak chemical bonds that occur when a hydrogen atom that is already participating in a covalent bond is attracted to another electronegative atom (such as oxygen, nitrogen or fluorine) within the same or different molecule. While they are not strong enough to hold atoms together to form molecules, they are strong enough to form bonds within and around large molecules, such as proteins and DNA.

Question 14

In the equation 2 H₂ + O₂ → 2 H₂O, the H₂ molecules are ________ and the H₂O molecules are ________.

Accepted Answer

The reactants (substances that are present at the beginning of a chemical reaction) are H2 and O2, while the products (substances that are formed during the reaction) are H2O. Therefore, H2 is a reactant and H2O is a product.

Question 15

What is the fundamental difference between covalent and ionic bonding?

Accepted Answer

The fundamental difference between covalent and ionic bonding is the sharing of electrons. Covalent bonds involve the sharing of electrons between two atoms, while ionic bonds involve the transfer of electrons from one atom to another, resulting in the formation of ions with opposite charges. In covalent bonding, the partners share a pair of electrons, whereas in ionic bonding, one partner accepts electrons from the other.

Question 16

In plants, the process of photosynthesis produces glucose (C₆H₁₂O₆) and oxygen from carbon dioxide and water. Which of the following options about photosynthesis is consistent with this statement?

Accepted Answer

The statement indicates that carbon dioxide and water are inputs for photosynthesis, and glucose and oxygen are outputs. Therefore, option A is correct as it states that all carbon atoms in glucose came from carbon dioxide. Option B is incorrect as the statement indicates a conservation of atoms. Option C is incorrect as it directly contradicts the statement. Option D is incorrect as it violates the known laws of chemistry.

Question 17

Water's surface tension and heat storage capacity are accounted for by its

Accepted Answer

Water's surface tension and heat storage capacity are due to its hydrogen bonds. The hydrogen bonds allow water molecules to stick together, creating surface tension. They also require a lot of energy to break, giving water a high heat storage capacity.

Question 18

The body uses atoms in different ways to accomplish different tasks. For example, one portion of the body's calcium supply strengthens bones, whereas another portion combines with proteins to stimulate blood clotting after tissue injury. Which of the following statements provides the most logical chemical explanation of calcium's ability to perform such different functions?

Accepted Answer

The calcium in bones is present in the form of calcium salts and is less reactive than the calcium ions found in the blood. This explains why it can perform the task of strengthening bones, while the more reactive form of calcium ions in the blood can combine with proteins for blood clotting after tissue injury. Option B, C, and D are incorrect as they are not supported or explained by any scientific evidence.

Question 19

Medicines are often administered in pill form. In many cases, the active ingredient of the pill (the drug) is joined to another substance by ________. This forms a(n) ________, which is stable in the dry environment of a pill bottle but dissociates under the wet conditions of the digestive system to release the drug to the body.

Accepted Answer

Ionic bonds often form salts, which are stable in dry conditions but can dissociate in water, releasing the active ingredient in the digestive system.

Question 20

The hydrogen atoms of a water molecule are bonded to the oxygen atom by ________ bonds, whereas neighboring water molecules are held together by ________ bonds.

Accepted Answer

The hydrogen atoms of a water molecule are bonded to the oxygen atom by polar covalent bonds because there is a strong electronegativity difference between oxygen and hydrogen, resulting in a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. Neighboring water molecules are held together by hydrogen bonds, which are weak electrostatic attractions between the partial positive charge of the hydrogen atom in one water molecule and the partial negative charge of the oxygen atom in another water molecule.

Quiz 2: The Chemical Basis of Life

The temperature of evaporation is much higher for water than for alcohol. Without knowing more about the chemistry of alcohol, which of the following is the most logical chemical explanation for this phenomenon?

Which of the following statements regarding the oxygen atom of a water molecule is true?

As ice melts

Water molecules stick to other water molecules because

Which of the following statements regarding chemical reactions is false?

Table salt is formed when

Which of the following statements about water is false?

The tendency of water molecules to stick together is referred to as

A(n) ________ forms when two atoms share electrons.

In a water molecule, hydrogen and oxygen are held together by a ________ bond.

A single water molecule (H-O-H) is held together by

A hydrogen atom has one electron. How many covalent bonds can hydrogen form?

________ are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.

In the equation 2 H₂ + O₂ → 2 H₂O, the H₂ molecules are and the H₂O molecules are .

What is the fundamental difference between covalent and ionic bonding?

In plants, the process of photosynthesis produces glucose (C₆H₁₂O₆) and oxygen from carbon dioxide and water. Which of the following options about photosynthesis is consistent with this statement?

Water's surface tension and heat storage capacity are accounted for by its

The hydrogen atoms of a water molecule are bonded to the oxygen atom by bonds, whereas neighboring water molecules are held together by bonds.

Quiz 2: The Chemical Basis of Life

The temperature of evaporation is much higher for water than for alcohol. Without knowing more about the chemistry of alcohol, which of the following is the most logical chemical explanation for this phenomenon?

Which of the following statements regarding the oxygen atom of a water molecule is true?

As ice melts

Water molecules stick to other water molecules because

Which of the following statements regarding chemical reactions is false?

Table salt is formed when

Which of the following statements about water is false?

The tendency of water molecules to stick together is referred to as

A(n) ________ forms when two atoms share electrons.

In a water molecule, hydrogen and oxygen are held together by a ________ bond.

A single water molecule (H-O-H) is held together by

A hydrogen atom has one electron. How many covalent bonds can hydrogen form?

________ are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.

In the equation 2 H2 + O2 → 2 H2O, the H2 molecules are ________ and the H2O molecules are ________.

What is the fundamental difference between covalent and ionic bonding?

In plants, the process of photosynthesis produces glucose (C6H12O6) and oxygen from carbon dioxide and water. Which of the following options about photosynthesis is consistent with this statement?

Water's surface tension and heat storage capacity are accounted for by its

The hydrogen atoms of a water molecule are bonded to the oxygen atom by ________ bonds, whereas neighboring water molecules are held together by ________ bonds.

In the equation 2 H₂ + O₂ → 2 H₂O, the H₂ molecules are and the H₂O molecules are .

In plants, the process of photosynthesis produces glucose (C₆H₁₂O₆) and oxygen from carbon dioxide and water. Which of the following options about photosynthesis is consistent with this statement?

The hydrogen atoms of a water molecule are bonded to the oxygen atom by bonds, whereas neighboring water molecules are held together by bonds.