You are provided with the following materials—vinegar, honey, mustard oil, water, glucose and wheat flour. Make any two pairs of materials where one material is soluble in the other. Now, make two pairs of materials where one material remains insoluble in the other material.
Soluble pairs include the following combinations. First, glucose dissolves in water—glucose is soluble in water and disappears when mixed. Second, vinegar mixes completely in water—vinegar is soluble in water and forms a uniform solution.
Insoluble pairs can be observed with different materials. First, mustard oil does not dissolve in water—oil forms a separate layer on top of water and does not mix even after stirring. Second, wheat flour does not dissolve in water—wheat flour remains suspended or settles at the bottom and does not disappear in water. Third, honey does not dissolve in mustard oil—honey and oil remain separate.
These observations are based on the principle that some materials dissolve completely in certain liquids while others do not mix and remain separate.
Explanation
The chapter explains on Pages 10-11 that soluble materials completely disappear when mixed in water, while insoluble materials do not mix and remain visible. The chapter also mentions on Page 12 that some liquids get completely mixed with water while others do not mix and form a separate layer. This question tests the application of solubility concepts to various common materials.
Solution Steps
Identify soluble pairs: Glucose dissolves in water, and vinegar mixes completely in water to form a uniform solution.
Identify insoluble pairs: Mustard oil forms a separate layer in water, wheat flour settles or suspends in water, and honey does not dissolve in mustard oil.
Conclude based on the principle that materials either dissolve completely or remain separate when mixed.