Question 1

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 2

A neutral atom of sodium (Na) has an atomic number of 11 and an atomic mass of 23. How many neutrons does it have?

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 3

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms

Question 4

Which element is most likely to form an ionic bond with chlorine (Cl)?

Accepted Answer

Sodium (Na)

Question 5

What is the maximum number of electrons that can occupy the second electron shell of an atom?

Accepted Answer

$$8$$

Question 6

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

Accepted Answer

Oxygen is more electronegative than hydrogen, creating partial charges

Question 7

Which of the following is a trace element essential for human life?

Accepted Answer

Iron (Fe)

Question 8

A radioactive isotope of carbon, carbon-14, is used in radiometric dating. What makes carbon-14 radioactive?

Accepted Answer

Its nucleus decays spontaneously, emitting particles and energy

Question 9

Which of the following best describes a hydrogen bond?

Accepted Answer

A bond formed when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom

Question 10

Which of the following is NOT a compound?

Accepted Answer

O$$_2 ($$oxygen gas)

Question 11

Which of the following best explains why noble gases like neon (Ne) are chemically inert?

Accepted Answer

They have a full valence shell of electrons

Question 12

Which of the following is an example of a mixture?

Accepted Answer

Sugar dissolved in water

Question 13

Which of the following statements about van der Waals interactions is correct?

Accepted Answer

They are weak attractions between molecules due to temporary hot spots of charge

Question 14

If an atom loses an electron, what type of ion does it become?

Accepted Answer

A cation

Question 15

Which of the following best describes the octet rule?

Accepted Answer

Atoms are most stable when their outermost electron shell is full, usually with eight electrons

Question 16

Which of the following is true about chemical reactions?

Accepted Answer

They involve the making and breaking of chemical bonds

Question 17

A molecule of methane (CH$$_4) $$contains what type of bonds between carbon and hydrogen?

Accepted Answer

Nonpolar covalent bonds

Question 18

Which of the following elements is NOT one of the six most abundant elements in living organisms (CHNOPS)?

Accepted Answer

Calcium (Ca)

Question 19

Which of the following changes would result in a different element?

Accepted Answer

Changing the number of protons

Question 20

A patient is injected with a radioactive isotope for a PET scan. Why is a radioactive isotope used in this medical procedure?

Accepted Answer

Radioactive isotopes emit detectable particles and energy as they decay

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

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