Question 1

Which of the following statements best explains why sodium chloride (NaCl) has properties different from both sodium and chlorine?

Accepted Answer

NaCl is a compound, and compounds have emergent properties that differ from the elements that form them.

Question 2

A radioactive isotope of carbon, $$^{14}C$$, is used in radiometric dating. If the half-life of $$^{14}C is 5$$,730 years, how much of a 100 g sample would remain after 11,460 years?

Accepted Answer

25 g

Question 3

Which of the following best describes the difference between a covalent bond and an ionic bond?

Accepted Answer

A covalent bond involves the sharing of electrons, while an ionic bond involves the transfer of electrons.

Question 4

Which element is most likely to form a polar covalent bond with hydrogen, based on electronegativity values?

Accepted Answer

Oxygen

Question 5

A PET scan uses radioactive tracers to monitor metabolic activity in tissues. Which property of radioactive isotopes makes this possible?

Accepted Answer

They emit particles and energy as they decay, which can be detected by imaging instruments.

Question 6

Which of the following best explains why noble gases such as neon (Ne) are chemically inert?

Accepted Answer

They have a full valence shell of electrons.

Question 7

A molecule of water ($$H_2O) $$has a bent shape. What is the main reason for this molecular geometry?

Accepted Answer

The positions of the valence orbitals and the repulsion between electron pairs around the oxygen atom.

Question 8

Which of the following is true about weak chemical interactions in biological systems?

Accepted Answer

They help maintain the structure and function of large biological molecules through reversible interactions.

Question 9

If an atom has an atomic number of 9 and a mass number of 19, how many neutrons does it have?

Accepted Answer

10

Question 10

Which of the following best describes a hydrogen bond?

Accepted Answer

An attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 11

Which of the following is an example of a trace element required by humans?

Accepted Answer

Iron (Fe)

Question 12

A scientist is studying a chemical reaction in which the products can become reactants for the reverse reaction. What is this type of reaction called?

Accepted Answer

A reversible reaction

Question 13

Which of the following best explains why salts such as NaCl dissociate easily in water?

Accepted Answer

Water molecules surround and separate the ions due to their polarity.

Question 14

Which of the following equations correctly represents the process of photosynthesis?

Accepted Answer

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

Question 15

Which of the following best describes chemical equilibrium in a reaction?

Accepted Answer

The forward and reverse reactions occur at the same rate, and the concentrations of reactants and products remain constant.

Question 16

A gecko can climb smooth walls due to van der Waals interactions. What is the basis of these interactions?

Accepted Answer

Temporary regions of positive and negative charge in molecules that are close together.

Question 17

Which of the following is true about isotopes of an element?

Accepted Answer

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

Question 18

Which of the following best explains why molecular shape is important in biology?

Accepted Answer

Molecular shape determines how molecules recognize and respond to each other.

Question 19

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

A bond in which electrons are shared equally between two atoms.

Question 20

Which of the following is the best example of an emergent property?

Accepted Answer

Table salt (NaCl) is edible, even though its elements sodium and chlorine are not.

Chapter 2: The Chemical Context of Life – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard