Question

When a hydrated chemical loses water of hydration attached to its molecules, the phenomenon is called:
A. Efflorescence
B. Radiation
C. Phosphorescence
D. Luminescence

Answer 1

Hint: A substance or its constituent elements that contains water is called hydrated chemical. This water is called water of crystallization. A hydrate is a salt associated with water of crystallization.

Complete answer:
Efflorescence is a process by which some substances lose their water of crystallisation completely or partially. This can happen when the crystals are exposed to dry air even for a short span of time. After this, it becomes powdery. Efflorescent substance that shows efflorescence.
Efflorescence is a spontaneous process. In the hydrated salt, It can take place, when the aqueous vapor pressure of the hydrate is more than the partial pressure of the water vapour in the air and their surfaces assume a powdery appearance.
Radiation is the process in which energy or particles from a source travels through space or any other mediums. Different forms of radiation are light, heat, microwaves, and wireless communications.
Phosphorescence is the emission of radiation in a like fluorescence but for longer times, so that the emission continues even after the excitation comes to an end.
Luminescence is a spontaneous emission of the light by a substance which is not resulting from heat. It can be said as a form of cold-body radiation. chemical reactions, electrical energy, subatomic motions, or stress on a crystal can be the cause of this phenomenon.

Hence, the answer to the above question is option A.

Additional Information:
The process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water to form a solution is called deliquescence. When the vapour pressure of the solution formed is less than the partial pressure of water vapour in the air, deliquescence occurs.

Note: A variety of hydrates are formed by transition metal sulphates. These crystallizes in only one form. Here the sulphate always binds to the metal, especially for those salts with less than six water ligands. Many of these sulphates are found in nature, as a result of weathering of mineral sulphides.