Question

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Explanation:

Step1: Identify the molecule structure

The diagram shows molecules with O (oxygen) and H (hydrogen) atoms. Each O is bonded to two H atoms, which is the structure of water ($H_2O$). Let's count the number of $H_2O$ molecules.
First molecule: O bonded to two H (1 $H_2O$). Second molecule: O bonded to two H (1 $H_2O$). Third molecule: O bonded to two H (1 $H_2O$). Wait, no, wait. Wait, the first O (top left) has two H, second O (top right) has two H, third O (bottom) has two H? Wait, no, the top right O: let's check the bonds. Top right O: two H atoms bonded. Top left O: two H. Bottom O: two H. Wait, but the formula for water is $H_2O$, so each $H_2O$ has one O and two H. So let's count the number of O atoms: three O atoms? Wait, no, the diagram: top left (O), top right (O), bottom (O). Each O has two H. Wait, but the top right O: the two H are bonded to it. So each O is part of a $H_2O$ molecule. So number of $H_2O$ molecules: 3? Wait, no, wait the top right O: the two H are attached to it, so that's one $H_2O$ (O with two H). Top left O: two H, one $H_2O$. Bottom O: two H, one $H_2O$. So total 3 $H_2O$ molecules? Wait, but maybe the question is about the number of water molecules. Wait, maybe the diagram is showing three $H_2O$ molecules? Wait, no, let's re - examine. Wait, the top left: O - H and O - H (so $H_2O$). Top right: O - H and O - H (so $H_2O$). Bottom: O - H and O - H (so $H_2O$). So three $H_2O$ molecules? Wait, but maybe the question is to count the number of water molecules. Alternatively, maybe the formula. Wait, each water molecule is $H_2O$, so for each O, there are two H. So if there are three O atoms, each with two H, then the number of $H_2O$ molecules is 3, since each $H_2O$ has one O and two H.

Step2: Confirm the count

Each $H_2O$ molecule consists of 1 O and 2 H. Looking at the diagram:

• First $H_2O$: O (top left) with two H.
• Second $H_2O$: O (top right) with two H.
• Third $H_2O$: O (bottom) with two H.

So the number of water molecules is 3.

Answer:

3