The oxidation is occurring on Calcium ions as it release one electron and reduction will be occurring on fluorine ion as it accepts one electron.
<u>Explanation:</u>
An element will undergo oxidation and form a positive ion on releasing one or more electrons from its valence shell. While reduction is occurred in a chemical reaction, then the element will be forming a negative ion with the acceptance of one or more electrons in its valence shell.
So in the given process of calcium fluoride, the one electron from the valence shell of calcium will be released making it as 
ions and this is termed as oxidation process. This one electron will be getting accepted by the fluorine ion and thus it will convert to 
ions. This process of acceptance of electrons is termed as reduction.
Answer:
A
Explanation:
increase in energy - hotter and/or more reactive
decrease in energy - colder and/or less reactive
Since it is going from a liquid to solid it will have a tighter arrangement of particles.
Answer:
Greenhouse gasses got their name from a greenhouse
Explanation:
Since greenhouses have plants inside in which the building lets sunlight in to the plants and greenhouse gasses trap heat. (sorry if my answer is confusing)
The correct answer is Freezing point
