**Dissolving in Water**

**Definition of Dissolving:** Dissolving is a process in which a solute (substance being dissolved) is evenly dispersed in a solvent (substance doing the dissolving) to form a homogenous mixture called a solution.

**Substances that can dissolve in water:**

Water is known as the "universal solvent" because it can dissolve a wide variety of substances due to its polarity. Polarity refers to the separation of electric charge within a molecule, causing one end of the molecule to be slightly positive and the other end to be slightly negative.

The substances that can dissolve in water can be categorized into three main groups:

1. **Gases:**
- Gases can dissolve in water to form a solution.
- Examples of gases that dissolve in water include oxygen (O2), carbon dioxide (CO2), and chlorine (Cl2).
- When gases dissolve in water, they form gas particles that are evenly distributed throughout the water.

2. **Liquids:**
- Some liquids are soluble in water, which means they can dissolve in water to form a solution.
- Examples of liquids that dissolve in water include ethanol (alcohol) and vinegar (acetic acid).
- When these liquids dissolve in water, their molecules become intermingled with the water molecules, resulting in a homogeneous mixture.

3. **Solids:**
- Many solids can dissolve in water to form a solution.
- Examples of solids that dissolve in water include sugar (sucrose), salt (sodium chloride), and baking soda (sodium bicarbonate).
- When solids dissolve in water, the individual particles of the solid break apart and become surrounded by water molecules. This process is called hydration.
- The dissolved particles (ions or molecules) are then evenly dispersed throughout the water, forming a solution.

Therefore, the correct answer is option 'D' - Solid, liquid, and gases. All three states of matter can dissolve in water to form a solution, as long as the substance is soluble in water.