Question 1

Which of the following best describes a compound?

Accepted Answer

A substance consisting of two or more elements in a fixed ratio.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

A radioactive isotope is useful in medicine because:

Accepted Answer

It can be used to track atoms through metabolism as a tracer.

Question 4

What is the atomic number of an element with 22 protons?

Accepted Answer

$$22$$

Question 5

How many neutrons are in an isotope of titanium with atomic number 22 and mass number 48?

Accepted Answer

$$26$$

Question 6

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

Accepted Answer

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

Question 7

Which type of bond is formed when one atom donates an electron to another atom, resulting in oppositely charged ions?

Accepted Answer

Ionic bond

Question 8

What is the main reason that weak chemical interactions, such as hydrogen bonds and van der Waals interactions, are important in biological systems?

Accepted Answer

They allow large biological molecules to maintain their functional forms and enable reversible interactions.

Question 9

Which of the following is true about chemical reactions?

Accepted Answer

They involve the making and breaking of chemical bonds.

Question 10

Given the chemical equation for photosynthesis: $$6 \mathrm{CO}_2 + 6 \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2$$, which are the reactants?

Accepted Answer

$$6 \mathrm{CO}_2$$ and $$6 \mathrm{H}_2\mathrm{O}$$

Question 11

Which of the following best describes chemical equilibrium?

Accepted Answer

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

Question 12

Which of the following food items is most like a compound?

Accepted Answer

A sandwich containing ham, lettuce, and tomato

Question 13

What do elements with atomic numbers 6, 14, and 22 have in common?

Accepted Answer

They have the same number of valence electrons and will form the same number of covalent bonds.

Question 14

Which statement about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 15

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

Accepted Answer

They have similar molecular shapes, allowing them to bind to the same receptors.

Question 16

Which of the following is a real-world application of radioactive isotopes?

Accepted Answer

PET scans to monitor cancer growth and metabolism

Question 17

Which of the following statements about electron shells is correct?

Accepted Answer

Electrons in higher shells have more potential energy than those in lower shells.

Question 18

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 19

Which of the following is an example of a polar covalent bond?

Accepted Answer

The bond between oxygen and hydrogen in a water molecule

Question 20

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

Accepted Answer

They are weak attractions that occur when electrons are distributed asymmetrically in molecules.

Chapter 2: The Chemical Context of Life: Elements, Atoms, and Chemical Bonds

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