The document defines various processes of state change including evaporation, regelation, boiling, and sublimation. Evaporation is identified as the correct term to describe a liquid spontaneously changing to vapor without any mention of temperature. Boiling and sublimation were eliminated as options because they require a liquid to reach a specific temperature or change directly from solid to gas.

1. PHYSICS:
JAMB, Q 51, 2005
The process whereby a liquid turns spontaneously
into vapour is called A. Evaporation B.Regelation
C.Boiling D. Sublimation

2. Solution
Topic/Subtopic: Change of State/Boiling and evaporation
In order to know which option is right, let us define them each
Evaporation: is the process by which liquid changes into vapour. It occurs at all temperature.
Regelation: is the melting and refreezing of ice block which is acted upon by a loaded string
Boiling : is the change of liquid into vapour at a temperature where the Saturated vapour pressure
equals the external atmospheric pressure. It occurs at a specific temperature.
Sublimation: is process by which a solid changes into gas without passing through liquid form.

3. From the definition above, the correct option is A) since no
specific temperature was stated.
Option B(regelation) is wrong it deals basically with ice block
Option C(Boiling) is wrong since boiing must occur at a certain
temperature which was not given in the question.
Option(D) is also wrong because it has nothing to do with liquid.