Question 1

Which of the following statements best describes an isotope?

Accepted Answer

An atom with the same number of protons but a different number of neutrons compared to other atoms of the same element.

Question 2

A radioactive isotope of carbon, $$^{14}C$$, is used in medical imaging. What makes $$^{14}C$$ radioactive compared to $$^{12}C$$?

Accepted Answer

$$^{14}C$$ has an unstable nucleus due to extra neutrons, causing it to decay over time.

Question 3

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

Accepted Answer

Their outermost electron shells are completely filled, making them stable and unreactive.

Question 4

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

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 5

Which of the following best describes a covalent bond?

Accepted Answer

A chemical bond formed by the sharing of a pair of valence electrons between two atoms.

Question 6

What is the main difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

In a polar covalent bond, electrons are shared unequally due to differences in electronegativity.

Question 7

Which of the following is an example of an ionic bond?

Accepted Answer

The bond between sodium ($$Na^+) $$and chloride ($$Cl^-) in $$table salt ($$NaCl).$$

Question 8

A patient is injected with a radioactive isotope as a tracer for a PET scan. Which property of radioactive isotopes makes this possible?

Accepted Answer

They emit detectable radiation as they decay, allowing tracking within the body.

Question 9

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number is the number of protons in the nucleus, which determines the element.

Question 10

Which of the following statements about chemical reactions is correct?

Accepted Answer

Chemical reactions rearrange the electrons among atoms but do not create or destroy atoms.

Question 11

A molecule of water ($$H_2O) is $$formed by which type of bond between hydrogen and oxygen?

Accepted Answer

Polar covalent bonds

Question 12

Which of the following best explains why morphine can mimic endorphins in the brain?

Accepted Answer

Morphine has a similar molecular shape to endorphins, allowing it to bind to the same receptors.

Question 13

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

Accepted Answer

They are weak attractions that occur when molecules are close together due to temporary partial charges.

Question 14

If an atom has 7 electrons in its valence shell, what is its most likely chemical behavior?

Accepted Answer

It tends to gain one electron to achieve a full valence shell, becoming a negatively charged ion.

Question 15

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom.

Question 16

Which of the following equations correctly represents the photosynthesis reaction?

Accepted Answer

$$6CO_2 + 6H_2O \xrightarrow{	ext{sunlight}} C_6H_{12}O_6$ + 6O_2$$

Question 17

Which of the following is a correct statement about chemical equilibrium?

Accepted Answer

At equilibrium, the forward and reverse reactions occur at the same rate, and the concentrations of reactants and products remain constant.

Question 18

A chlorine atom has 17 protons and 18 electrons. What is its charge and what is it called?

Accepted Answer

It has a charge of $$-1$$ and is called an anion.

Question 19

Which of the following best describes the concept of bonding capacity?

Accepted Answer

The number of covalent bonds an atom can form, usually equal to the number of unpaired electrons in its valence shell.

Question 20

Which of the following scenarios best illustrates the importance of molecular shape in biological function?

Accepted Answer

A drug molecule with a shape similar to a natural hormone binds to the same receptor and triggers a similar response.

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

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