Question 1

Which of the following statements best explains why sodium chloride (NaCl) has properties different from those of its constituent elements, sodium and chlorine?

Accepted Answer

A compound has emergent properties that arise from the specific arrangement and bonding of its atoms.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Oxygen, carbon, hydrogen, and nitrogen

Question 3

A radioactive isotope of carbon, $$^{14}C$$, is used in radiometric dating. If the half-life of $$^{14}C is 5$$,730 years, how much of a 100 g sample remains after 11,460 years?

Accepted Answer

$$25\ \mathrm{g}$$

Question 4

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 5

Why are trace elements such as iodine essential for life, even though they make up less than 0.01% of body mass?

Accepted Answer

They are necessary for specific biochemical processes, such as hormone production.

Question 6

Which of the following statements about electron shells and energy levels is correct?

Accepted Answer

Electrons can move between shells by absorbing or releasing energy in fixed amounts.

Question 7

A patient is given a radioactive tracer to monitor thyroid function. Which property of radioactive isotopes makes this possible?

Accepted Answer

They have the same chemical behavior as stable isotopes but emit detectable radiation.

Question 8

Which of the following best explains why noble gases such as helium are chemically inert?

Accepted Answer

They have a full valence shell of electrons.

Question 9

What type of bond is formed when two atoms share a pair of valence electrons equally?

Accepted Answer

Nonpolar covalent bond

Question 10

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation has lost electrons and is positively charged; an anion has gained electrons and is negatively charged.

Question 11

Which of the following scenarios best illustrates the concept of emergent properties in compounds?

Accepted Answer

Hydrogen and oxygen gases combine to form water, which is a liquid with unique properties.

Question 12

Which statement about hydrogen bonds is correct?

Accepted Answer

They form when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

Question 13

A molecule of water ($$H_2O) is $$described as polar. What does this mean?

Accepted Answer

The molecule has regions of partial positive and partial negative charge due to unequal sharing of electrons.

Question 14

Which of the following best describes a chemical reaction at equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate.

Question 15

Which of the following is an example of a weak chemical interaction that is important for the three-dimensional structure of large biological molecules?

Accepted Answer

Hydrogen bonds

Question 16

Which of the following best explains why geckos can climb smooth vertical surfaces?

Accepted Answer

Van der Waals interactions between the gecko's toe hairs and the surface

Question 17

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are in the outermost shell and determine an atom's chemical behavior.

Question 18

Which of the following equations correctly represents the process of photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 19

A scientist discovers a new element with an atomic number of 15 and a mass number of 31. How many neutrons does this atom have?

Accepted Answer

$$16$$

Question 20

Which of the following best explains why morphine and endorphins can both bind to the same receptors in the brain?

Accepted Answer

They have similar molecular shapes that fit the receptor sites.

Chapter 2: The Chemical Context of Life – Study Notes

스터디 가이드 - 연습 문제

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