$$\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$$

Question 1

Which of the following best explains why iodine is considered an essential element for human health?

Accepted Answer

Iodine is necessary for the production of thyroid hormones, which regulate metabolism.

Question 2

An atom of carbon has 6 protons, 6 neutrons, and 6 electrons. What is the atomic number and mass number of this atom?

Accepted Answer

Atomic number: 6, Mass number: 12

Question 3

Which statement best describes the relationship between valence electrons and chemical reactivity?

Accepted Answer

Atoms with incomplete valence shells tend to form chemical bonds to achieve stability.

Question 4

Which of the following elements is most likely to form ionic bonds with chlorine?

Accepted Answer

Sodium (Na)

Question 5

A neutral atom of magnesium has 12 protons and 12 electrons. If it loses two electrons, what is the resulting charge of the ion?

Accepted Answer

$$+2$$

Question 6

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electron pairs between atoms.

Question 7

Given the atomic structure diagram, which subatomic particle determines the chemical identity of an element?

Accepted Answer

Proton

Question 8

Which of the following is a trace element essential for life, and what is its primary biological role?

Accepted Answer

Iron; necessary for oxygen transport in blood

Question 9

If an atom has 8 protons, 8 neutrons, and 10 electrons, what is its net charge?

Accepted Answer

$$-2$$

Question 10

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

Accepted Answer

Their valence shells are completely filled, making them stable.

Question 11

Which of the following is the correct formula for calculating the mass number of an atom?

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 12

Which property of electrons allows them to occupy specific energy levels around the nucleus?

Accepted Answer

Their quantized energy states

Question 13

Which of the following best describes the difference between an isotope and an ion?

Accepted Answer

Isotopes have different numbers of neutrons; ions have different numbers of electrons.

Question 14

Which of the following elements is most abundant in living organisms?

Accepted Answer

Oxygen (O)

Question 15

A patient is diagnosed with anemia due to iron deficiency. Which chemical property of iron makes it essential for oxygen transport?

Accepted Answer

Iron can reversibly bind to oxygen in hemoglobin due to its ability to change oxidation states.

Question 16

Which of the following best describes electronegativity?

Accepted Answer

The attraction of an atom for electrons in a covalent bond.

Question 17

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same column have similar chemical properties due to the same number of valence electrons.

Question 18

Which of the following is a multi-step process that explains how atoms form molecules in living cells?

Accepted Answer

Atoms interact through chemical bonds, sharing or transferring electrons to achieve stable valence shells, forming molecules.

Question 19

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Question 20

Which of the following best explains why water (H$$_2O) is a $$polar molecule?

Accepted Answer

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

Atoms, Elements, and Chemical Bonds: Foundations of Biological Chemistry

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