Question 1

Which of the following statements best explains why sodium chloride (NaCl) has properties different from those of its constituent elements, sodium and chlorine?

Accepted Answer

The emergent properties of NaCl result from the fixed ratio and ionic bonding between sodium and chlorine atoms.

Question 2

Which of the following elements makes up the largest percentage of human body mass?

Accepted Answer

Oxygen

Question 3

A radioactive isotope of iodine is often used in medical imaging to track thyroid function. What property of radioactive isotopes makes them useful as tracers in biological systems?

Accepted Answer

They decay spontaneously, emitting particles and energy that can be detected.

Question 4

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally, resulting in partial charges on the atoms.

Question 5

Which equation correctly represents the chemical reaction for photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 6

An atom of carbon has 6 protons, 6 neutrons, and 6 electrons. What is its atomic number and mass number?

Accepted Answer

Atomic number: 6, Mass number: 12

Question 7

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have a full valence shell of electrons, making them stable and unlikely to react.

Question 8

Which of the following is true about hydrogen bonds in biological molecules?

Accepted Answer

Hydrogen bonds form between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom.

Question 9

Which of the following statements about trace elements is correct?

Accepted Answer

Trace elements are required by organisms in very small quantities.

Question 10

A molecule of water ($$H_2O) is $$held together by which type of bond, and what property does this bond impart to the molecule?

Accepted Answer

Polar covalent bond; gives water partial positive and negative charges.

Question 11

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

Accepted Answer

A molecule consists of two or more atoms held together by covalent bonds, while a compound consists of two or more different elements in a fixed ratio.

Question 12

Which of the following scenarios best illustrates the concept of emergent properties in compounds?

Accepted Answer

Hydrogen and oxygen gases are both flammable, but when combined to form water, the compound is non-flammable and essential for life.

Question 13

Which of the following best describes the formation of ions in an ionic bond?

Accepted Answer

One atom strips electrons from another, resulting in oppositely charged ions that attract each other.

Question 14

If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number: 11, Mass number: 23

Question 15

Which of the following is a real-world example of a chemical reaction involving the making and breaking of chemical bonds?

Accepted Answer

The conversion of carbon dioxide and water into glucose and oxygen during photosynthesis.

Question 16

Which of the following best explains why electrons in different shells have different potential energies?

Accepted Answer

Electrons farther from the nucleus have higher potential energy because they are less tightly held.

Question 17

Which of the following is true about van der Waals interactions?

Accepted Answer

They are weak attractions that occur when electrons are unevenly distributed in molecules.

Question 18

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are in the outermost shell and determine the chemical behavior of an atom.

Chapter 2: The Chemical Context of Life – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard