Question 1

Which of the following best describes an element?

Accepted Answer

A substance at its base that cannot be broken down by chemical means

Question 2

Which trace element deficiency is most likely to cause goiter and mental retardation in humans?

Accepted Answer

Iodine

Question 3

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

Accepted Answer

$$16$$

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 5

Which type of chemical bond is formed when atoms share electrons equally?

Accepted Answer

Nonpolar covalent bond

Question 6

Why is chlorine (Cl) highly reactive as an element?

Accepted Answer

It only needs one more electron to achieve an octet configuration

Question 7

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

Accepted Answer

The oxygen atom is more electronegative, causing electrons to be shared unequally

Question 8

Which of the following is a correct example of a chemical reaction?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 9

Which of the following statements about valence electrons is true?

Accepted Answer

Valence electrons determine the chemical properties of an element

Question 10

A radioactive isotope of phosphorus, $$^{32}P$$, is commonly used in biology labs. What is its primary application?

Accepted Answer

Labeling DNA and RNA

Question 11

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the attraction between oppositely charged ions

Question 12

Which element is NOT one of the four major elements found in living organisms?

Accepted Answer

Sodium

Question 13

If a neutral atom has 11 protons, how many electrons does it have?

Accepted Answer

$$11$$

Question 14

Which of the following is a property of covalent bonds?

Accepted Answer

Electrons are shared between atoms

Question 15

Which of the following is true about chemical reactions?

Accepted Answer

Atoms are rearranged, but not created or destroyed

Question 16

Which of the following best explains why sodium (Na) forms a cation in ionic compounds?

Accepted Answer

Sodium loses an electron, resulting in a positive charge

Question 17

Which of the following is a real-world application of fluorine as a trace element?

Accepted Answer

PET scans using fluorodeoxyglucose to measure glucose metabolism

Question 18

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally due to differences in electronegativity

Question 19

Which of the following statements about electrons is correct?

Accepted Answer

Electrons determine the atom's size

Question 20

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

Accepted Answer

They are weak attractions between molecules due to temporary charge differences

The Chemical Basis of Life: Elements, Atoms, and Chemical Bonds

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