Question

Acrystalline powder that contains water of crystallization or hydration; this water can be liberated either during manipulations or an exposure to a low – humidity environment – then the powder will become sticky and pasty, or it may even liquefy. Such a powder is called:

• A. Eutectic
• B. Hygroscopic
• C. Deliquescent
• D. Efflorescent

Answer 1

The Correct Option is D

The question involves identifying a type of crystalline powder based on its behavior with water of crystallization. Let's examine the options one by one:

1. Eutectic: Eutectic mixtures consist of two or more components that solidify together at a specific composition and temperature. These do not involve water of crystallization and hence are not relevant to the description provided.
2. Hygroscopic: A hygroscopic substance absorbs moisture from the surrounding air but does not necessarily contain water of hydration within its crystal structure. While hygroscopic substances may become damp, they do not become sticky, pasty, or liquefy to the extent described in the question.
3. Deliquescent: Deliquescent substances absorb moisture from the air to the extent that they dissolve in the absorbed water, essentially liquefying. While this seems partially applicable, the description in the question focuses on losing water of crystallization, rather than absorbing water.
4. Efflorescent: Efflorescent substances lose their water of crystallization when exposed to air, leading to a change in physical properties such as becoming powdery or crumbly. This behavior matches the description in the question, where the crystalline powder becomes sticky, pasty, or liquefies upon losing water.

Therefore, the correct answer is Efflorescent, as this type of powder typically undergoes changes when it loses its water of crystallization to the environment.