Question 1

Which of the following statements best describes an element?

Accepted Answer

A substance that cannot be broken down any further by chemical reactions.

Question 2

Given an atom with atomic number $$Z = 8$$ and atomic mass $$A = 16$$, how many neutrons does it have?

Accepted Answer

$$8$$

Question 3

Which of the following best explains why water molecules are polar?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons and partial charges.

Question 4

A radioactive isotope of carbon, $$^{14}C$$, is used in dating fossils. What property makes it useful for this purpose?

Accepted Answer

It decays spontaneously, allowing measurement of its ratio over time.

Question 5

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of valence electrons between atoms.

Question 6

If sodium ($$Na) $$has an atomic number of $$11$$, how many electrons does a neutral sodium atom have?

Accepted Answer

$$11$$

Question 7

Which of the following is true about van der Waals interactions?

Accepted Answer

They are weak attractions caused by temporary shifts in electron distribution.

Question 8

Which of the following atoms is most likely to form a cation?

Accepted Answer

An atom with one valence electron.

Question 9

What is the main difference between a polar and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity; nonpolar covalent bonds involve equal sharing.

Question 10

Which of the following best describes the role of hydrogen bonds in biological systems?

Accepted Answer

They are weak interactions that can collectively stabilize large biological molecules.

Question 11

A molecule of carbon dioxide ($$CO_2) $$has which type of covalent bonds?

Accepted Answer

Double covalent bonds between carbon and each oxygen.

Question 12

Which of the following elements is most electronegative?

Accepted Answer

Oxygen ($$O)$$

Question 13

If an atom has 6 protons, 8 neutrons, and 6 electrons, what is its atomic mass?

Accepted Answer

$$14$$

Question 14

Which of the following is a real-world example of an ionic bond?

Accepted Answer

The bond between sodium and chlorine in table salt ($$NaCl).$$

Question 15

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

Their valence shells are completely filled.

Question 16

Which of the following is true about isotopes?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 17

Which of the following best describes the relationship between atomic number and the number of protons in an atom?

Accepted Answer

Atomic number is equal to the number of protons.

Question 18

Which of the following scenarios would most likely result in the formation of an anion?

Accepted Answer

An atom gains an electron.

Question 19

Which of the following is the correct formula for calculating atomic mass?

Accepted Answer

$$	ext{Atomic mass} = 	ext{number of protons} + 	ext{number of neutrons}$$

Question 20

Which of the following best describes the effect of electronegativity on covalent bond formation?

Accepted Answer

A large difference in electronegativity between two atoms leads to a polar covalent bond.

Chapter 2: The Chemical Context of Life – General Biology Study Notes

스터디 가이드 - 연습 문제