Question 1

Which subatomic particle determines the chemical reactivity of an element?

Accepted Answer

Electron

Question 2

An atom has 7 protons, 7 neutrons, and 7 electrons. Which element is it, and how many electron shells does it have?

Accepted Answer

Nitrogen; 2 shells

Question 3

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of one or more pairs of electrons between atoms

Question 4

What is the maximum number of electrons that can occupy the 2p orbitals?

Accepted Answer

$$6$$

Question 5

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons

Question 6

A sodium atom loses one electron to become a sodium ion. What is the charge of the resulting ion?

Accepted Answer

$$+1$$

Question 7

Which type of bond is primarily responsible for holding together the two strands of DNA?

Accepted Answer

Hydrogen bonds

Question 8

Why are noble gases such as helium and neon chemically inert?

Accepted Answer

They have a full complement of valence electrons

Question 9

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons

Question 10

Which of the following elements is NOT one of the four that make up 99% of matter in living cells?

Accepted Answer

Calcium

Question 11

A molecule of oxygen gas ($$O_2) is $$held together by which type of bond?

Accepted Answer

Double covalent bond

Question 12

Which of the following is true about hydrogen bonds?

Accepted Answer

They are dynamic and can be easily broken and reformed

Question 13

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the attraction between oppositely charged ions

Question 14

How many valence electrons does a carbon atom have?

Accepted Answer

$$4$$

Question 15

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

Accepted Answer

The bond between sodium and chlorine in table salt

Question 16

Which statement about electron shells is correct?

Accepted Answer

The second shell can hold up to 8 electrons

Question 17

Which of the following best explains why enzymes are required to form or break covalent bonds in biological systems?

Accepted Answer

Covalent bonds are strong and require significant energy to form or break

Question 18

Which of the following is a property of noncovalent bonds such as hydrogen bonds and ionic bonds?

Accepted Answer

They are critical for the 3D structure of biological molecules

Question 19

Which of the following best describes the relationship between protons, neutrons, and atomic mass?

Accepted Answer

Atomic mass = number of protons + number of neutrons

Question 20

Which of the following is a consequence of the 3D shape of molecules formed by covalent bonds?

Accepted Answer

Molecules can interact specifically with other molecules, such as enzymes with substrates

Basic Chemistry for Biology: Atoms, Elements, and Chemical Bonds

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