Question 1

Which of the following best describes an element?

Accepted Answer

A substance that has certain chemical properties and cannot be easily broken apart.

Question 2

A neutral atom of sodium (Na) has an atomic number of 11 and an atomic mass 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 have the same number of protons but different numbers of neutrons.

Question 4

Which type of chemical bond is responsible for holding the sodium and chloride ions together in table salt (NaCl)?

Accepted Answer

Ionic bond

Question 5

A molecule of water ($H_2O$) is formed by which type of bond between hydrogen and oxygen?

Accepted Answer

Covalent bond

Question 6

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

Accepted Answer

It has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom.

Question 7

What is the main reason why water has a high heat capacity?

Accepted Answer

Water molecules are held together by hydrogen bonds, which require a lot of energy to break.

Question 8

A solution with a pH of 3 is how many times more acidic than a solution with a pH of 6?

Accepted Answer

$10^3 = 1000$ times more acidic

Question 9

Which of the following best describes a base in aqueous solution?

Accepted Answer

A substance that accepts $H^+$ ions or releases $OH^-$ ions into the solution.

Question 10

A patient’s blood pH is measured at 7.25. Which of the following best describes this condition?

Accepted Answer

The patient is experiencing acidosis.

Question 11

Which of the following is a property of hydrophilic substances?

Accepted Answer

They are 'water loving' and mix well with water.

Question 12

Which of the following best explains why sodium ions ($Na^+$) and chloride ions ($Cl^-$) are considered electrolytes?

Accepted Answer

They dissociate in water to form ions that can conduct electricity.

Question 13

Which of the following is true regarding the atomic number of an element?

Accepted Answer

It is equal to the number of protons in the atom.

Question 14

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between polar molecules or polar regions of large molecules.

Question 15

If a molecule has polar covalent bonds, what does this mean about the sharing of electrons?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on the atoms.

Question 16

Which of the following is NOT a characteristic of water that is important for life?

Accepted Answer

It is hydrophobic and does not mix with most substances.

Question 17

A molecule that releases $H^+$ ions in solution is best described as:

Accepted Answer

An acid

Question 18

Which of the following best explains why acids and bases are considered highly reactive in biological systems?

Accepted Answer

They can break chemical bonds and change the shapes of complex molecules.

Question 19

Which of the following is the correct formula for calculating the atomic weight of an atom?

Accepted Answer

$	ext{Atomic weight} = 	ext{Number of protons} + 	ext{Number of neutrons}$

Question 20

A student mixes table salt (NaCl) in water and observes that it dissolves completely. Which property of water is most responsible for this observation?

Accepted Answer

Water is a polar molecule and can dissolve ionic compounds.

Chapter 2: The Chemical Level of Organization – Fundamentals of Anatomy & Physiology

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