Question 1

Which subatomic particle is responsible for the chemical properties of an element, and where is it located in the atom?

Accepted Answer

Electron; orbiting the nucleus

Question 2

Given the atomic number and mass number for carbon ($$6$$ and $$12$$ respectively), how many neutrons does a typical carbon atom have?

Accepted Answer

$$6$$

Question 3

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

Accepted Answer

Hydrogen bonds in ice form a lattice that spaces molecules farther apart, making ice less dense.

Question 4

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

Accepted Answer

Sodium donates an electron to chlorine, resulting in oppositely charged ions that attract.

Question 5

Which of the following statements about water is FALSE?

Accepted Answer

Water is a nonpolar molecule.

Question 6

A solution has a pH of $$4. $$How does its hydrogen ion concentration compare to a solution with a pH of $$6$$?

Accepted Answer

It is $$100$$ times higher.

Question 7

Which of the following best describes a buffer in biological systems?

Accepted Answer

A molecule that resists changes in pH by absorbing excess H$$^+ or OH$^-$$ ions.

Question 8

Which of the following is a correct representation of the dissociation of water?

Accepted Answer

$$ \mathrm{H_2O \rightleftharpoons H^+ + OH^-} $$

Question 9

Which property of water allows insects to walk on its surface, as shown in the provided image?

Accepted Answer

Surface tension due to cohesion among water molecules

Question 10

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

Accepted Answer

A molecule is two or more atoms joined together; a compound is two or more different elements joined together.

Question 11

Which of the following is true about isotopes?

Accepted Answer

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

Question 12

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

Accepted Answer

Oxygen is more electronegative, causing electrons to spend more time near it, creating partial charges.

Question 13

Which of the following is a real-life application of radioisotopes in medicine?

Accepted Answer

Radioisotopes are used in PET scans to image organs and tissues.

Question 14

Which of the following best describes the octet rule?

Accepted Answer

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

Question 15

Which of the following is a correct example of a polar covalent bond?

Accepted Answer

$$ \mathrm{H_2O} $$

Question 16

Which of the following best explains why salt (NaCl) dissolves in water?

Accepted Answer

The polar water molecules surround and stabilize the Na$$^+$$ and Cl$$^-$$ ions, separating them.

Question 17

Which of the following best describes the relationship between atomic number and atomic mass?

Accepted Answer

Atomic number is the number of protons; atomic mass is the sum of protons and neutrons.

Question 18

Which of the following is a property of water that helps regulate temperature in living organisms?

Accepted Answer

Water has a high heat capacity, allowing it to absorb and release heat slowly.

Question 19

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation has lost electrons and is positively charged; an anion has gained electrons and is negatively charged.

Chemistry of Life: Foundations for Microbiology

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