Question

Which of the following is not soluble in water?
A.Salt
B.Sugar
C.Oxygen
D.Sand

Answer 1

Hint: When the complex is attracted by positive to negative, making a cohesive structure. As we know that salt is an ionic compound of sodium and chlorine. The ionic compounds form cations and anions. The species of cations and anions attracted with water. So if the compound is attracted to water by dipole attraction, it may be soluble in water.

Complete step by step answer:
- Salt dissolves in water due to electrical charges and due to both water and salt compounds are polar, with opposite charges on opposite sides in the molecule. Salt and water both are in ionic nature but the bond between salt and water is covalent bond. When salt is mixed with water, the salt dissolves because the covalent bonds of water are stronger than the ionic bonds in the salt molecules.
-Sugar has hydroxyl group which is bonding with water by hydrogen bond. Hydrogen bonds are important intermolecular forces which describe the shape of molecules. Here, Sugar has hydroxyl groups thus water has the same group. That is the reason that sugar dissolves in water.
-Oxygen contains small particles which get trapped in water molecules and utilized by water organisms for substances. So, oxygen is soluble in water.
-The bond of water is not strong to dissolve the particles of sand. Water can separate only polar particles but sand is not polar. Water doesn’t have energy to break the particles of sand.

Hence option D is correct.

Note:
Solubility is dependent on the bonding of compounds with water. Water is a polar compound and it dissolves only polar compounds. It’s important to know how compound is interacted with water and solute can be dissolved. All ionic compounds are soluble in water because of hydration energy.