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 their constituent elements.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

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

Accepted Answer

$$12.5\ \mathrm{g}$$

Question 4

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 5

Which of the following is a trace element required by humans and is often added to table salt to prevent deficiency?

Accepted Answer

Iodine

Question 6

A patient is injected with a radioactive tracer to monitor cancer growth. Which property of radioactive isotopes makes this possible?

Accepted Answer

They emit detectable particles and energy as they decay.

Question 7

Which of the following best explains why noble gases such as helium and neon are chemically inert?

Accepted Answer

They have full valence electron shells.

Question 8

If an atom has an atomic number of 7 and a mass number of 15, how many neutrons does it have?

Accepted Answer

$$8$$

Question 9

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally between two atoms, resulting in partial charges.

Question 10

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

Accepted Answer

Table salt (NaCl) has properties different from both sodium metal and chlorine gas.

Question 11

Which of the following best explains why water molecules are able to form hydrogen bonds with each other?

Accepted Answer

Water molecules have polar covalent bonds, resulting in partial positive and negative charges.

Question 12

A gecko can climb smooth surfaces due to the collective strength of many weak interactions between its toe hairs and the wall. What type of interaction is primarily responsible for this phenomenon?

Accepted Answer

Van der Waals interactions

Question 13

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number is the number of protons in the nucleus and defines the element.

Question 14

Which of the following is true about chemical reactions in living organisms?

Accepted Answer

They involve the making and breaking of chemical bonds.

Question 15

Which of the following best explains why isotopes of the same element have different mass numbers?

Accepted Answer

They have different numbers of neutrons.

Question 16

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

Accepted Answer

Valence electrons are involved in forming chemical bonds between atoms.

Question 17

A scientist finds a fossil and measures the ratio of parent to daughter isotopes. If the half-life of the parent isotope is $$1 	imes 10^6$ years and the ratio indicates three half-lives have passed, how old is the fossil?

Accepted Answer

$$3 	imes 10^6$ years

Question 18

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

Accepted Answer

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

Question 19

Which of the following is an example of a reversible chemical reaction?

Accepted Answer

$$3H_2 + N_2$ \rightleftharpoons 2NH_3$$

Question 20

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.

Chapter 2: The Chemical Context of Life – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard