Question 1

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

Accepted Answer

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

Question 2

A scientist discovers a new element with an atomic number of 15 and a mass number of 31. How many neutrons does this element have?

Accepted Answer

$$31 - 15 = 16$$ neutrons

Question 3

Which property of water allows it to act as an effective coolant for organisms through sweating?

Accepted Answer

High heat of vaporization

Question 4

If a solution has a pH of 4, how many times more acidic is it than a solution with a pH of 6?

Accepted Answer

$$10^2 = 100$ times more acidic

Question 5

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by transferring electrons from one atom to another, resulting in attraction between oppositely charged ions.

Question 6

What is the main reason ice floats on liquid water?

Accepted Answer

Hydrogen bonds in ice are more rigid and form an open structure, making ice less dense than liquid water.

Question 7

Which of the following elements is NOT part of the CHNOPS group that makes up 95% of the body weight of organisms?

Accepted Answer

Calcium

Question 8

A buffer in human blood helps maintain a pH of 7.4. What would happen if the blood pH dropped below 7.0?

Accepted Answer

Acidosis would occur, which is life-threatening.

Question 9

Which of the following is true about isotopes?

Accepted Answer

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

Question 10

Which statement best describes the octet rule?

Accepted Answer

Atoms are most stable when their outermost shell contains eight electrons.

Question 11

Which of the following molecules is a compound?

Accepted Answer

$$CO_2$$

Question 12

What is the role of valence electrons in chemical bonding?

Accepted Answer

They determine whether an atom will give up, accept, or share electrons to achieve stability.

Question 13

Which of the following best explains why water is a good solvent for ionic compounds?

Accepted Answer

Water's polarity allows it to surround and separate ions in ionic compounds.

Question 14

A molecule of glucose has the formula $$C_6H_{12}O_6$. How many atoms are present in one molecule of glucose?

Accepted Answer

$$6 + 12 + 6 = 24$$ atoms

Question 15

Which of the following is a consequence of water's high heat capacity for living organisms?

Accepted Answer

Organisms are protected from rapid temperature changes.

Question 16

Which type of chemical bond is responsible for the structure of DNA and proteins?

Accepted Answer

Hydrogen bonds

Question 17

If an atom has 8 protons, 8 neutrons, and 8 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number: 8, Mass number: 16

Question 18

Which of the following best describes a buffer?

Accepted Answer

A chemical or combination of chemicals that keeps pH within normal limits.

Question 19

Which of the following is true about the periodic table?

Accepted Answer

Atoms in the same group share the same chemical binding characteristics.

Question 20

Which of the following is a real-world example of water's adhesive property?

Accepted Answer

Water climbing up the vessels in plant stems through capillary action.

Chapter 2: Basic Chemistry – Foundations for Biology

Study Guide - Practice Questions