Question 1

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element is a substance made of only one type of atom, while a compound consists of two or more different elements chemically bonded together.

Question 2

A neutral atom of sodium (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 3

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 4

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 5

If the pH of a solution changes from 5 to 2, how does the concentration of hydrogen ions $$[H^+]$$ change?

Accepted Answer

It increases by $$10^{3} = 1000$ times

Question 6

Which of the following best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water is a polar molecule, so it can surround and separate ions and polar molecules.

Question 7

Which emergent property of water allows insects like water striders to walk on the surface of a pond?

Accepted Answer

Cohesion due to hydrogen bonding

Question 8

A solution contains a solute and a solvent. Which statement is correct?

Accepted Answer

The solute is the substance dissolved in the solvent.

Question 9

Which of the following substances is most likely to be hydrophobic?

Accepted Answer

A long hydrocarbon chain, such as oil

Question 10

When water dissociates, which ions are produced?

Accepted Answer

Hydrogen ion ($$H^+) $$and hydroxide ion ($$OH^-)$$

Question 11

A buffer is added to a solution. What is its primary effect?

Accepted Answer

It minimizes changes in pH when acids or bases are added.

Question 12

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between like molecules; adhesion is the attraction between different molecules.

Question 13

A chlorine atom has 17 protons and 18 neutrons. What is its mass number?

Accepted Answer

$$17 + 18 = 35$$

Question 14

Which of the following is true about ions?

Accepted Answer

Ions are atoms or molecules that have gained or lost electrons, resulting in a net charge.

Question 15

Which property of water helps moderate Earth's climate by absorbing and releasing large amounts of heat with only slight temperature changes?

Accepted Answer

High specific heat

Question 16

A molecule of methane ($$CH_4) $$has how many valence electrons around the central carbon atom?

Accepted Answer

8 valence electrons

Question 17

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

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart, making ice less dense than liquid water.

Question 18

A student is given the atomic number and mass number of an unknown element. Which formula should they use to find the number of neutrons?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Question 19

Which of the following is a real-life example of a buffer system in the human body?

Accepted Answer

The bicarbonate buffer system maintaining blood pH

Question 20

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

General Biology Chapter 2: Chemistry Study Guide – Step-by-Step Guidance

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