From the following organic compounds given below, choose one compound in each case which relates to the description [i] to [iv]:

[Ethyne, ethanol, acetic acid, ethene, methane].

(i) An unsaturated hydrocarbon used for welding purposes.

(ii) An organic compound whose functional group is carboxyl.

(iii) A hydrocarbon which on catalytic hydrogenation gives a saturated hydrocarbon.

(iv) An organic compound used as a thermometric liquid.

Name the following:

(i) Process by which ethane is obtained from ethene.

(ii) A hydrocarbon which contributes towards the greenhouse effect.

(iii) Distinctive reaction that takes place when ethanol is treated with acetic acid.

(iv) The property of elements by virtue of which atoms of the element can link to each other in the form of a long chain or ring structure.

(v) Reaction when an alkyl halide is treated with alcoholic potassium hydroxide.

(i) Why is pure acetic acid known as glacial acetic acid ?

(ii) Give a chemical equation for the reaction between ethyl alcohol and acetic acid.

Find the odd one out and explain:

C₃H₈, C₅H₁₀, C₂H₆, CH₄