Concept explainers
Polar molecules
a. dissolve in lipids.
b. are hydrophobic.
c. form covalent bonds.
d. form ionic bonds.
Introduction:
Molecules can be broadly classified as polar or nonpolar. Polar molecules have an unequal distribution of electrons in their outermost orbitals giving a positive charge to one end of the molecule and negative charge to the other end. This unequal distribution of charges is responsible for the unique properties of polar molecules.
Answer to Problem 1MC
Correct answer:
Polar molecules form ionic bonds.
Explanation of Solution
Explanation for the correct answer:
Ionic bonds are formed by electrostatic interactions between oppositely charged ions. The atoms, which have gained extra electrons, are negatively charged (anions) and the atoms, which have lost electrons, are positively charged (cations). Such atoms can combine together by an ionic bond and form polar molecules. Option (d) is given that polar molecules form ionic bonds. Hence, option (d) is correct.
Explanation for incorrect answers:
Option (a) is given that polar molecules dissolve in lipids. Polar molecules are attracted to other polar molecules. Water is a polar molecule which makes all polar molecules water soluble. Oil is a nonpolar molecule that makes all nonpolar molecules lipid soluble. So, it is an incorrect answer.
Option (b) is given that polar molecules are hydrophobic. Polar molecules can dissolve in water which means that they are hydrophilic or ‘water-loving.’ So, it is an incorrect option.
Option (c) is given that polar molecules form covalent bonds. Covalent bonds are formed by the sharing of electron pairs between the atoms. This sharing of electrons gives the molecule a stable bond in which the attractive and repulsive forces are balanced. So, this is an incorrect option.
Hence options (a), (b), and (c) are incorrect.
Therefore, polar molecules are formed by ionic bonds between a cation and an anion. They are hydrophilic or water-soluble in nature.
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Chapter 3 Solutions
Biology: Life on Earth (11th Edition)
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