Q: Which equation correctly represents the relationship between mass number, protons, and neutrons?

$$\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$$

Q: Which equation represents the chemical reaction for the formation of water from hydrogen and oxygen?

$$2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$$

Question 1

Which four elements make up about 96% of the weight of most living organisms?

Accepted Answer

Carbon, Hydrogen, Nitrogen, Oxygen

Question 2

A compound is best defined as:

Accepted Answer

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

Question 3

Fluoride is added to municipal water primarily to:

Accepted Answer

Reduce tooth decay

Question 4

Which subatomic particle determines the atomic number of an element?

Accepted Answer

Proton

Question 5

A nitrogen atom has 7 protons and its most common isotope has 7 neutrons. A radioactive isotope of nitrogen has 9 neutrons. What is the atomic number and mass number of this radioactive nitrogen?

Accepted Answer

Atomic number: 7, Mass number: 16

Question 6

Why are radioactive isotopes useful as tracers in research on the chemistry of life?

Accepted Answer

Their radioactive emissions can be detected, allowing scientists to track the movement of atoms

Question 7

Which equation correctly represents the relationship between mass number, protons, and neutrons?

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 8

Which type of chemical bond involves the sharing of electrons between atoms?

Accepted Answer

Covalent bond

Question 9

What is the main reason water molecules form hydrogen bonds with each other?

Accepted Answer

Water molecules are polar, with partial positive and negative charges

Question 10

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water due to hydrogen bonding

Question 11

What is the effect of evaporative cooling on the surface of a liquid?

Accepted Answer

The surface cools down as the hottest molecules evaporate

Question 12

Which equation represents the chemical reaction for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2	ext{H}_2 + 	ext{O}_2 ightarrow 2	ext{H}_2	ext{O}$$

Question 13

Blood and most other biological fluids are classified as aqueous solutions because:

Accepted Answer

Water is the solvent, dissolving polar or charged solutes

Question 14

Compared to a basic solution at pH 9, the same volume of an acidic solution at pH 4 has how many times more $$	ext{H}^+$$ ions?

Accepted Answer

$$10^5$$ times more $$	ext{H}^+$$ ions

Question 15

Which property of water is responsible for the formation of sweat droplets on the skin after exercise?

Accepted Answer

Cohesion due to hydrogen bonding

Question 16

What holds together the ions in a crystal of table salt ($$	ext{NaCl}$$)?

Accepted Answer

Ionic bonds between oppositely charged ions

Question 17

Which of the following best describes a buffer?

Accepted Answer

A substance that minimizes changes in pH

Question 18

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

Accepted Answer

Using PET scans to monitor brain activity

Question 19

Which term describes the tendency of molecules of the same kind to stick together?

Accepted Answer

Cohesion

Question 20

How many covalent bonds can a carbon atom form?

Accepted Answer

Four

Chapter 2: The Chemical Basis of Life – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards