Question 1

Which of the following best describes an element?

Accepted Answer

A pure substance consisting of only one kind of atom.

Question 2

If an atom has an atomic number of 8 and an atomic mass of 16, how many neutrons does it have?

Accepted Answer

$16 - 8 = 8$ neutrons

Question 3

Which statement about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 4

Which of the following best explains why sodium (Na) forms an ionic bond with chlorine (Cl) to make table salt (NaCl)?

Accepted Answer

Sodium transfers an electron to chlorine, resulting in oppositely charged ions that attract each other.

Question 5

Which of the following molecules is a compound?

Accepted Answer

$H_2O$

Question 6

What is the main difference between polar and nonpolar covalent bonds?

Accepted Answer

Polar covalent bonds share electrons unequally due to differences in electronegativity, while nonpolar covalent bonds share electrons equally.

Question 7

Which of the following is the correct order of bond strength from strongest to weakest?

Accepted Answer

Covalent > Ionic > Hydrogen

Question 8

A carbon atom has 6 protons, 6 neutrons, and 6 electrons. What is its atomic number and atomic mass?

Accepted Answer

Atomic number: $6$, Atomic mass: $12$

Question 9

Which of the following best describes a molecule?

Accepted Answer

A group of atoms joined together by chemical bonds.

Question 10

Which element is most abundant in the human body (excluding water)?

Accepted Answer

Oxygen

Question 11

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical reactivity of an element.

Question 12

Which of the following is a trace element required in small amounts by living organisms?

Accepted Answer

Iron

Question 13

If an atom has a full outer shell of electrons, it is:

Accepted Answer

Inert

Question 14

Which of the following best explains why water ($H_2O$) is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, so electrons are shared unequally, creating partial charges.

Question 15

Which of the following is the correct formula for glucose?

Accepted Answer

$C_6H_{12}O_6$

Question 16

A radioactive isotope differs from a stable isotope in that it:

Accepted Answer

Emits particles and energy as it decays.

Question 17

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the attraction between oppositely charged ions.

Question 18

Which of the following is true about hydrogen bonds?

Accepted Answer

They occur between molecules with polar covalent bonds.

Question 19

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

Accepted Answer

Their outer electron shells are full, so they do not readily form chemical bonds.

Question 20

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

Accepted Answer

Double covalent bond

Atomic Structure, Elements, and Chemical Bonds: Foundations of General Biology

Study Guide - Practice Questions