Solubility in Water

Introduction:
In chemistry, solubility refers to the ability of a substance to dissolve in a solvent, such as water. Solubility depends on the nature of the solute and solvent, as well as the temperature and pressure. Some substances readily dissolve in water, while others do not.

Solubility of Sand:
Sand is primarily composed of silicon dioxide (SiO2) which is an insoluble substance in water. This means that sand does not dissolve or mix with water. Instead, sand particles will settle at the bottom when mixed with water, forming a suspension.

Solubility of Mustard Oil:
Mustard oil is a non-polar substance, meaning it does not have a significant positive or negative charge. Water, on the other hand, is a polar molecule, with a slight positive charge on the hydrogen atoms and a slight negative charge on the oxygen atom. Since "like dissolves like," polar substances tend to dissolve in polar solvents, and non-polar substances tend to dissolve in non-polar solvents.

Since mustard oil is non-polar and water is polar, mustard oil is not soluble in water. Instead, it will form separate layers when mixed with water, with the oil floating on top due to its lower density.

Solubility of Plastic:
Plastic is a broad term that encompasses many different types of materials, some of which are soluble in water, while others are not. However, most common types of plastic, such as polyethylene, polypropylene, and polystyrene, are hydrophobic and insoluble in water. They do not have polar groups that can interact with water molecules, making them non-polar and thus not soluble in water.

Solubility of Sugar:
Sugar, or sucrose, is a polar substance composed of glucose and fructose molecules. It has multiple polar groups, including hydroxyl (OH) groups, which can form hydrogen bonds with water molecules. This makes sugar highly soluble in water. When sugar is added to water, the sugar molecules dissociate and form hydrogen bonds with water, dispersing evenly throughout the solvent.

Conclusion:
From the given options, only sugar (option B) is soluble in water. Sand, mustard oil, and plastic are all insoluble in water due to their non-polar nature or lack of polar groups. Solubility depends on the nature of the substances being dissolved and the solvent in which they are dissolved.