AP Biology Quiz 1 Ch. 2,3
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Which of the following best explains the distinction between biology and chemistry?
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Biologists study living things, whereas chemists study nonliving things
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Biology has a hierarchy of structural levels, whereas chemistry does not
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Chemists study molecules, whereas biologists do not
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Chemical systems have emergent properties; biological systems do not
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There is no clear distinction because the two sciences are parts of the same whole
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Quiz 1 in AP Biology for Ch. 2,3 in Reece and Campbell book.
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- 2.
Review the valences of carbon, oxygen, hydrogen, and nitrogen, and then determine which of the following molecules is most likely to exist.
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O=C-H
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H H I I H-O-C-C=O I H
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H H I I H-C-H-C=O I H
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O I H-N-H
Correct Answer
A. H H I I H-O-C-C=O I HExplanation
The given molecule, H-O-C-C=O, is most likely to exist because it follows the valences of carbon, oxygen, hydrogen, and nitrogen. Carbon has a valence of 4, oxygen has a valence of 2, hydrogen has a valence of 1, and nitrogen has a valence of 3. In the given molecule, carbon has four bonds, oxygen has two bonds, hydrogen has one bond, and nitrogen has three bonds. Therefore, this molecule is the most likely to exist based on the valences of the atoms involved.Rate this question:
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- 3.
What bond does NH4 form wilt Cl to make ammonium chloride salt?
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Nonpolar covalent bond
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Polar covalent bond
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Ionic bond
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Hydrogen bond
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Covalent bond
Correct Answer
A. Ionic bondExplanation
NH4 forms an ionic bond with Cl to make ammonium chloride salt. Ionic bonds occur when there is a transfer of electrons between atoms, resulting in the formation of oppositely charged ions. In this case, NH4 donates one electron to Cl, forming NH4+ and Cl- ions. These ions are attracted to each other due to their opposite charges, creating an ionic bond.Rate this question:
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- 4.
Which of the following best describes the relationship between the atoms described below? Atom 1 Atom 2 1H 3H 1 1
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They are isomers.
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They are polymers.
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They are isotopes
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They are ions.
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They are both radioactive.
Correct Answer
A. They are isotopesExplanation
Isotopes are atoms of the same element that have different numbers of neutrons. In this case, Atom 1 and Atom 2 are both hydrogen atoms (1H), but Atom 1 has 1 neutron while Atom 2 has 3 neutrons. Therefore, they are isotopes of each other.Rate this question:
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- 5.
What do the four elements most abundant in life-carbon, oxygen, hydrogen, and nitrogen-have in common?
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They all have the same number of valence electrons.
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Each element exists only in one isotopic form.
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They are equal in electronegativity.
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They are elements produced only by living cells.
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They all have unpaired electrons in their valence shells,
Correct Answer
A. They are elements produced only by living cells. -
- 6.
What are the chemical properties of atoms whose valence shells are filled with electrons?
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They form ionic bonds in aqueous solutions.
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They form covalent bonds in aqueous solutions.
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They are stable and unreactive
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They exhibit similar chemical behaviors
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Both C and D are correct.
Correct Answer
A. Both C and D are correct.Explanation
Atoms whose valence shells are filled with electrons are stable and unreactive. This is because the valence shell is the outermost shell of an atom and when it is completely filled, the atom has achieved a stable electron configuration. As a result, these atoms do not readily participate in chemical reactions. Additionally, atoms with filled valence shells exhibit similar chemical behaviors because they have similar electron configurations, leading to similar chemical properties.Rate this question:
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- 7.
What are the maximum number of covalent bonds an element with atomic number 16 can make with hydrogen?
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1
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2
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3
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4
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5
Correct Answer
A. 1Explanation
An element with atomic number 16 is sulfur. Sulfur has 6 valence electrons, and it needs 2 more electrons to achieve a stable octet. Therefore, it can form 2 covalent bonds with hydrogen to fulfill its electron requirement. However, the question asks for the maximum number of covalent bonds, so the correct answer is 1.Rate this question:
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- 8.
Oxygen has an atomic number of 8. Therefore, it must have
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8 protons
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8 electrons
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16 neutrons
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Only A and B are correct.
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A, B, and C are correct.
Correct Answer
A. Only A and B are correct.Explanation
Since oxygen has an atomic number of 8, it means that it has 8 protons in its nucleus. The number of protons in an atom is equal to the number of electrons, so oxygen also has 8 electrons. The number of neutrons in an atom can vary, but it is not determined by the atomic number. Therefore, the correct answer is that oxygen has 8 protons and 8 electrons, making option A and B correct.Rate this question:
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- 9.
Which of the following best describes chemical equilibrium?
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Reactions continue with no effect on the concentrations of reactants and products.
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Concentrations of products are high.
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Reactions have stopped.
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Reactions stop only when all reactants have been converted to products.
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There are equal concentrations of reactants and products.
Correct Answer
A. Reactions continue with no effect on the concentrations of reactants and products.Explanation
Chemical equilibrium is a state in a chemical reaction where the rates of the forward and reverse reactions are equal, resulting in no net change in the concentrations of reactants and products over time. This means that while the reactions are still occurring, the concentrations of reactants and products remain constant. Therefore, the correct answer is "Reactions continue with no effect on the concentrations of reactants and products."Rate this question:
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- 10.
If the pH of a solution is increased from pH 8 to pH 9, it means that
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Concentration of H+ is 10 times greater than what it was at pH 8.
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Concentration of H+ is 100 times less than what it was at pH 8.
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Concentration of OH- is 10 times greater than what it was at pH 8.
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Concentration of OH- is 100 times greater than what it was at pH 8.
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Concentration of H+ is greater and the concentration of OH- is less than at pH 8.
Correct Answer
A. Concentration of H+ is 10 times greater than what it was at pH 8.Explanation
When the pH of a solution increases from 8 to 9, it indicates that the concentration of H+ ions has increased. A change of one unit in pH represents a tenfold change in the concentration of H+ ions. Therefore, the concentration of H+ ions is 10 times greater than it was at pH 8.Rate this question:
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- 11.
What is the maximum number of hydrogen bonds a water molecule acan form with neighboring water molecules?
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One
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Two
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Three
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Four
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Five
Correct Answer
A. FiveExplanation
Water molecules can form a maximum of four hydrogen bonds. Each water molecule has two hydrogen atoms and two lone pairs of electrons. These hydrogen atoms can form hydrogen bonds with the lone pairs of electrons on neighboring water molecules. Since each water molecule has two lone pairs of electrons, it can form a maximum of four hydrogen bonds with four neighboring water molecules. Therefore, the correct answer is four.Rate this question:
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- 12.
Which bonds must be broken for water to vaporize?
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Ionic bonds
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Nonpolar covalent bonds
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Polar covalent bonds
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Hydrogen bonds
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Both C and D are correct.
Correct Answer
A. Both C and D are correct.Explanation
Both polar covalent bonds and hydrogen bonds must be broken for water to vaporize. Polar covalent bonds are the bonds between the oxygen and hydrogen atoms within a water molecule, while hydrogen bonds are the attractions between the positive hydrogen atom of one water molecule and the negative oxygen atom of another water molecule. Breaking these bonds allows the water molecules to escape from the liquid phase and become a gas during vaporization.Rate this question:
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- 13.
One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus,H2CO3 <--> HCO3- + H+ If the pH of the blood drops, one would expect
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A decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-.
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The concentration of hydroxide ion (OH-) to increase.
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The concentration of bicarbonate ion (HCO3-) to increase.
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The HCO3- to act as a base and remove excess H+ with the formation of H2CO3.
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The HCO3- to act as an acid and remove excess H= with the formation of H2CO3.
Correct Answer
A. The HCO3- to act as a base and remove excess H+ with the formation of H2CO3.Explanation
When the pH of the blood drops, it means that the concentration of hydrogen ions (H+) has increased. In order to restore pH stability, the bicarbonate ion (HCO3-) acts as a base and removes the excess hydrogen ions by combining with them to form carbonic acid (H2CO3). This reaction helps to maintain the balance between carbonic acid and bicarbonate ions, thus stabilizing the pH of the blood.Rate this question:
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- 14.
When an ice cube cools a drink 1 degree C, which of the following is true?
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Molecule collisions in the drink increase.
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Kinetic energy in the drink decreases.
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A kilocalorie of heat is transferred to the water.
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A kilocalorie of heat is transferred to the ice.
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Exaporation of the water increases.
Correct Answer
A. A kilocalorie of heat is transferred to the ice.Explanation
When an ice cube cools a drink 1 degree C, a kilocalorie of heat is transferred to the ice. This is because heat always flows from a higher temperature object to a lower temperature object, so the heat from the drink is transferred to the colder ice cube in order to equalize the temperatures. This transfer of heat causes the ice cube to melt and absorb the energy, resulting in a decrease in temperature of the drink.Rate this question:
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- 15.
Which of the following statements is completely correct?
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H2CO3 is a weak acid, and NaOH is a weak base
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H2CO3 is a strong acid, and NaOH is a strong base.
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NH3 is a weak base and, and H2CO3 is a strong acid.
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NH3 is a strong base, and HCl is a weak acid.
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NH3 is a weak base, and HCl is a strong acid.
Correct Answer
A. NH3 is a weak base, and HCl is a strong acid.Explanation
The given statement is correct because NH3 (ammonia) is a weak base, as it only partially dissociates in water to form hydroxide ions. HCl (hydrochloric acid) is a strong acid, as it completely dissociates in water to form hydrogen ions. Therefore, NH3 can accept fewer hydrogen ions compared to HCl, making NH3 a weak base and HCl a strong acid.Rate this question:
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- 16.
Which of the following ionizes completely in solution and is therefore a strong base?
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NaOH
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HCl
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NH3
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H2CO3
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NaCl
Correct Answer
A. NaClExplanation
NaCl is not a strong base because it does not ionize completely in solution. It is actually a salt that is formed from the reaction between a strong acid (HCl) and a strong base (NaOH). When NaCl is dissolved in water, it dissociates into Na+ and Cl- ions, but it does not contribute to the concentration of hydroxide ions (OH-) in the solution, which is characteristic of a strong base.Rate this question:
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- 17.
Buffers are substances that help resist shifts in pH by
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Releasing H+ in acidic solutions.
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Releasing H+ in basic solutions.
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Releasing OH- in basic solutions.
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Combining with OH- in acidicsolutions.
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Combining with H+ in basic solutions.
Correct Answer
A. Releasing H+ in basic solutions.Explanation
Buffers are substances that help maintain the pH of a solution by resisting changes in acidity or alkalinity. In basic solutions, the pH is higher, meaning it is more alkaline. To resist a shift towards acidity, a buffer should release H+ ions, which are acidic. Therefore, the correct answer is releasing H+ in basic solutions. This helps to counteract the increase in pH and maintain a stable pH level.Rate this question:
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- 18.
Whater's high specific heat is mainly a consequence of the
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Small size of the water molecules.
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High specific heat of oxygen and hydrogen atoms.
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Absorption and release of heat when hydrogen bonds break and form.
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Fact that water is a poor heat conductor.
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Inability of water to dissapate heat into dry air.
Correct Answer
A. Absorption and release of heat when hydrogen bonds break and form.Explanation
Water's high specific heat is mainly a consequence of the absorption and release of heat when hydrogen bonds break and form. This is because water molecules are able to form hydrogen bonds with each other, which are relatively strong and require a significant amount of energy to break. When heat is added to water, these hydrogen bonds absorb the energy, causing the water molecules to move faster and increase in temperature. Conversely, when heat is removed from water, the hydrogen bonds release the energy, helping to stabilize the temperature. This property allows water to resist temperature changes and maintain a stable environment, making it an excellent regulator of temperature in both living organisms and the environment.Rate this question:
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Nov 08, 2008Quiz Created by
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