Pure water consists almost entirely of ……………

Options

A. ions
B. atoms
C. ions and molecules
D. molecules

Explanation

To answer the question "Pure water consists almost entirely of ……………", we can follow these steps:

### Step 1: Understand the Composition of Pure Water
Pure water is primarily composed of water molecules (H₂O). Each molecule consists of two hydrogen atoms and one oxygen atom.

### Step 2: Consider the Dissociation of Water
While pure water can dissociate into ions (H⁺ and OH⁻), this process occurs to a very minimal extent. The degree of dissociation is less than 1%, meaning that for every 100 water molecules, less than one molecule dissociates into ions.

### Step 3: Identify the Main Component
Since the question asks what pure water consists of "almost entirely," we focus on the predominant component. Given that the vast majority of water remains in the molecular form, we conclude that pure water consists almost entirely of water molecules.

### Step 4: State the Answer
Thus, the answer to the question is: Pure water consists almost entirely of **water molecules**.

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