Question 1

Which four elements make up approximately 96% of the mass of the human body?

Accepted Answer

Carbon, Hydrogen, Oxygen, Nitrogen

Question 2

An atom of carbon-14 has 6 protons, 8 neutrons, and 6 electrons. What is its atomic number and mass number?

Accepted Answer

Atomic number = 6, Mass number = 14

Question 3

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

Accepted Answer

Covalent bond

Question 4

Why is water less dense as a solid than as a liquid?

Accepted Answer

Hydrogen bonds stabilize and space out water molecules in a crystalline structure

Question 5

Which property of water allows it to resist changes in temperature and act as a buffer?

Accepted Answer

High specific heat

Question 6

A solution has a pH of 3. How many times more acidic is it than a solution with a pH of 5?

Accepted Answer

$$10^2 = 100$

Question 7

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 8

What is the main reason sodium (Na) and chlorine (Cl) form an ionic bond?

Accepted Answer

Sodium donates an electron to chlorine, resulting in opposite charges that attract

Question 9

Which of the following is a consequence of hydrogen bonding in water?

Accepted Answer

Cohesion, adhesion, and surface tension

Question 10

If a molecule has atoms with very different electronegativities, what type of covalent bond will likely form?

Accepted Answer

Polar covalent bond

Question 11

Which statement best explains why water is an effective solvent for ionic compounds?

Accepted Answer

Water's polarity allows it to surround and separate ions

Question 12

A chemical reaction obeys the Law of Conservation of Matter. What does this mean?

Accepted Answer

The total number of atoms before and after the reaction remains the same

Question 13

Which of the following best describes the difference between heat and temperature?

Accepted Answer

Heat is the transfer of thermal energy; temperature measures the average kinetic energy of molecules

Question 14

What happens to water molecules during evaporative cooling?

Accepted Answer

Molecules with the highest kinetic energy leave as gas, lowering the average temperature

Question 15

Which of the following is true about acids in aqueous solutions?

Accepted Answer

Acids donate $$H^+$$ ions, increasing their concentration

Question 16

If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number = 11, Mass number = 23

Question 17

Which of the following best explains why carbon is the backbone of many biological molecules?

Accepted Answer

Carbon is tetravalent and can form up to four covalent bonds

Question 18

Which of the following is a trace element required in minute amounts for human health?

Accepted Answer

Iron (Fe)

Question 19

What is the main difference between a compound and an element?

Accepted Answer

A compound consists of two or more different elements in a fixed ratio; an element is a substance that cannot be broken down into simpler substances

Question 20

Which of the following best describes the arrangement of electrons in an atom's shells?

Accepted Answer

The first shell holds up to 2 electrons, the second and third shells hold up to 8 electrons each

Basic Chemistry for General Biology: Chapter 2 Study Notes

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