Question 1

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

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds arrange water molecules in a lattice structure, increasing the space between them.

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 type of atomic bond is responsible for the formation of table salt (NaCl)?

Accepted Answer

Ionic bond

Question 4

Which property of water allows insects to walk on its surface?

Accepted Answer

High surface tension due to hydrogen bonding

Question 5

If a carbon atom has 6 protons, 8 neutrons, and 6 electrons, what is its atomic mass?

Accepted Answer

$$6 + 8 = 14$$ amu

Question 6

Which of the following best describes a radioactive isotope?

Accepted Answer

An atom that spontaneously decays, releasing energy that can damage DNA

Question 7

What is the main difference between covalent and ionic bonds?

Accepted Answer

Covalent bonds involve sharing electrons, while ionic bonds involve the transfer of electrons.

Question 8

Which of the following molecules is held together primarily by polar covalent bonds?

Accepted Answer

H$$_2O$$

Question 9

A molecule of glucose (C$$_6H$_{12}O$_6) $$has how many total atoms?

Accepted Answer

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

Question 10

Which statement about elements and compounds is correct?

Accepted Answer

Compounds are composed of two or more different elements.

Question 11

Which subatomic particle determines the identity of an element?

Accepted Answer

Proton

Question 12

What is the charge of an ion formed when an atom loses one electron?

Accepted Answer

Positive

Question 13

Which of the following best explains why water has a high heat capacity?

Accepted Answer

Hydrogen bonds between water molecules require more energy to break.

Question 14

Which of the following is NOT a property of water?

Accepted Answer

Water has a low surface tension

Question 15

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic mass and charge?

Accepted Answer

Atomic mass: $$17 + 18 = 35$$ amu; Charge: neutral

Question 16

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a slightly positive hydrogen atom and a slightly negative atom (such as oxygen or nitrogen) in another molecule.

Question 17

Which of the following is true about isotopes?

Accepted Answer

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

Question 18

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

Accepted Answer

Water molecules are polar, allowing them to surround and dissolve many substances.

Question 19

Which of the following is a real-world example of a compound?

Accepted Answer

NaCl

Question 20

A molecule contains 2 hydrogen atoms and 1 oxygen atom. What is its molecular mass if the atomic masses are: H = 1 amu, O = 16 amu?

Accepted Answer

$$2 	imes 1 + 16 = 18$$ amu

Chemistry Foundations for General Biology: Atoms, Elements, and Water

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