Question

The direct change from solid to gaseous state is referred to as:
A.Dissociation
B.Decomposition
C.Sublimation
D.deliquescence

Answer 1

Hint: Check the phase transitions of the given states. The transition can be from solid to liquid state, liquid to gas and solid to gas as given and many more. Depending on the type of transition we have the process names.

Complete answer:
 The transition of a substance directly from solid to gas state, without passing through the liquid state is known as Sublimation.
Answer is Option(C)
During the phase transition from solid to gas, there is no effect on the chemical identity of the substance. The reverse of Sublimation i.e. change from gas to solid state is known as Deposition. Example of Sublimation is DRY ICE. Dry Ice undergoes a physical change when it sublimates from the solid to gaseous state without first melting into a liquid. The same $C{{O}_{2}}$ is still present; it just undergoes a phase change to become a colorless gas.
The substances that are sublime are called Sublimely Substances.

So, the correct answer is “Option C”.

Note:
 Study about the phase transitions of various states, the reversible and irreversible processes of the transitions along with their daily life examples. One can also study the proper mechanism involved behind the phase transitions and what factors can lead to the transitions and their respective changes on the compound undergoing the transition. The concepts regarding first order phase transition and second order phase transition can also be studied followed by the latent heat study. A good knowledge of thermodynamics can help in better understanding the transitions. The six ways a substance can change between three phases i.e. solid , liquid and gas should be studied well. Moreover, the study regarding kinetic energies and intermolecular forces between the particles is also very helpful.