Question 1

Which of the following statements best explains why sodium chloride (NaCl) has properties different from those of sodium and chlorine individually?

Accepted Answer

NaCl is a compound formed by a fixed ratio of sodium and chlorine atoms, resulting in new chemical properties.

Question 2

Which element makes up the largest percentage of human body mass, and what is its approximate percentage?

Accepted Answer

Oxygen, 65.0%

Question 3

A neutral atom of carbon has an atomic number of 6 and a mass number of 12. How many neutrons does it have?

Accepted Answer

$$6$$

Question 4

Radioactive isotopes are useful in medical imaging because:

Accepted Answer

They decay spontaneously, releasing particles and energy that can be tracked in metabolic processes.

Question 5

Which of the following best describes the difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

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

Question 6

Which of the following molecules contains a nonpolar covalent bond?

Accepted Answer

CH$$_4$$

Question 7

What happens to the electrons when a potassium atom bonds with a chlorine atom?

Accepted Answer

Potassium loses an electron and chlorine gains an electron.

Question 8

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

A hydrogen atom attached to an electronegative atom in one molecule is attracted to an electronegative atom in an adjacent molecule.

Question 9

Which type of bond occurs within a water molecule (H$$_2O$$)?

Accepted Answer

Polar covalent bonds

Question 10

If an atom has 6 valence electrons, which element is it most likely to be?

Accepted Answer

Sulfur

Question 11

Which of the following best explains why morphine and endorphins can both bind to the same receptors in the brain?

Accepted Answer

They have similar molecular shapes, allowing them to fit into the same receptor sites.

Question 12

Which of the following is true about chemical reactions?

Accepted Answer

Chemical reactions involve both the making and breaking of chemical bonds.

Question 13

Photosynthesis is represented by the following chemical equation: $$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2. $$What are the reactants in this reaction?

Accepted Answer

$$CO_2$$ and $$H_2O$$

Question 14

Which of the following best describes the concept of chemical equilibrium?

Accepted Answer

The concentrations of reactants and products remain constant because the forward and reverse reactions occur at the same rate.

Question 15

Which of the following is a trace element required by humans in minute quantities?

Accepted Answer

Iron

Question 16

Which of the following best describes an ionic bond?

Accepted Answer

Valence electrons from one atom are donated to another atom, resulting in oppositely charged ions that attract each other.

Question 17

Which of the following scenarios is an example of a van der Waals interaction?

Accepted Answer

Temporary regions of positive and negative charge in a molecule cause weak attractions between molecules.

Question 18

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

Accepted Answer

They have a full valence shell of electrons, making them stable and unlikely to react.

Question 19

Which of the following is true about isotopes of an element?

Accepted Answer

Isotopes have different numbers of neutrons.

Question 20

Which of the following best describes the role of potential energy in electron shells?

Accepted Answer

Electrons in shells farther from the nucleus have higher potential energy.

Chapter 2: The Chemical Context of Life – General Biology Study Notes

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