Chapter 6, Problem 31A

Summary Introduction

Introduction :

The force that holds the substances together is called a chemical bond. Chemical bonds are of two types- covalent and ionic bonds. Covalent bond is formed by sharing of electrons. An ionic bond results from electrical attraction between two oppositely charged atoms or group of atoms. Substances formed by ionic bonds are called ionic compounds.

Answer to Problem 31A

Correct answer :

The correct answer is option (C) It is composed of ionic bonds.

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) It is composed of ionic bonds. Water is a molecule formed by covalent bonds that link two hydrogen atoms with an oxygen atom. Water has a bent shape and the electrons are not shared equally between hydrogen and oxygen, therefore hydrogen bonds form among the molecules. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) It has a pH of 7.0. pH is the measure of concentration of hydrogen ions (H⁺) in a solution. Pure water is neutral and has a pH value of 7.0. So, this is an incorrect option.

Option (B) It is composed of polar molecules. Molecules that have an unequal distribution of charges are called polar molecules. Polarity is the property of having two opposite poles i.e. they have oppositely charged regions. The water molecule has an unequal distribution of electrons. In addition, the bent shape of water makes the oxygen end of the molecule slightly negative and the hydrogen end of the molecule slightly positive. So, this is an incorrect answer.

Option (D) It is a good solvent. There are two components in a solution- solvent and solute. The solvent is a substance in which another substance is dissolved. A solute is a substance that is dissolved in the solvent. An example of a solution is salt water. Water is known as a universal solvent as many substances can be dissolved in it. Hence, this is an incorrect answer.