Question 1

Which of the following best describes an emergent property, as illustrated by the formation of sodium chloride (NaCl) from sodium and chlorine?

Accepted Answer

A property that arises only when sodium and chlorine combine, and is not present in the individual elements.

Question 2

A patient is diagnosed with a thyroid disorder due to insufficient iodine intake. Which category does iodine fall under in terms of biological necessity?

Accepted Answer

Trace element required by only some species

Question 3

An atom of magnesium has an atomic number of 12 and a mass number of 24. How many neutrons does it have?

Accepted Answer

$$24 - 12 = 12$$

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 5

Which of the following best explains why electrons in the second shell of an atom have more potential energy than those in the first shell?

Accepted Answer

They are farther from the nucleus and thus have higher potential energy.

Question 6

A neutral atom of phosphorus has an atomic number of 15. How many electrons are in its valence shell?

Accepted Answer

5

Question 7

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 8

What is the main reason that water (H$$_2O) is a $$polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

Question 9

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

Accepted Answer

A molecule consists of atoms held together by covalent bonds, while an ionic compound consists of ions held together by electrostatic attraction.

Question 10

Which of the following is an example of a weak chemical bond that is crucial for the structure of DNA and protein folding?

Accepted Answer

Hydrogen bond

Question 11

A gecko can climb smooth walls 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 12

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

Accepted Answer

They have a full valence shell of electrons.

Question 13

Which of the following best describes the role of molecular shape in biological function?

Accepted Answer

Molecular shape determines how molecules recognize and interact with each other.

Question 14

If a carbon atom forms four single covalent bonds, what is the resulting molecular geometry around the carbon atom?

Accepted Answer

Tetrahedral

Question 15

Which of the following best describes the process of an electron moving from a lower to a higher energy shell?

Accepted Answer

The electron absorbs energy and moves farther from the nucleus.

Question 16

A sodium atom (Na) transfers an electron to a chlorine atom (Cl), resulting in the formation of Na$$^+$$ and Cl$$^-. $$What type of bond holds these ions together in NaCl?

Accepted Answer

Ionic bond

Question 17

Which of the following is a real-life example of the importance of trace elements in human health?

Accepted Answer

Iron is required for oxygen transport in blood.

Question 18

Which of the following best explains why water is an excellent solvent for ionic compounds like NaCl?

Accepted Answer

Water molecules are polar and can surround and separate ions.

Question 19

Which of the following equations correctly represents the conservation of matter in the reaction: $$Fe_2O_3 + C \rightarrow Fe + CO$$?

Accepted Answer

$$Fe_2O_3 + 3C \rightarrow 2Fe + 3CO$$

Question 20

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

Accepted Answer

The atomic number determines the number of protons, which in turn determines the number of electrons and thus the chemical properties.

Chapter 2: The Chemical Context of Life – General Biology Study Notes

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