Which is the best method to prepare cyclohexene from cyclohexanol?

Methyl alcohol on oxidation with acidified $K_2Cr_2O_7$ gives

Name the reagents used in the following reactions:
$(i)$ Oxidation of a primary alcohol to carboxylic acid.
$(ii)$ Oxidation of a primary alcohol to aldehyde.
$(iii)$ Bromination of phenol to $2,4,6-$tribromophenol.
$(iv)$ Benzyl alcohol to benzoic acid.
$(v)$ Dehydration of propan$-2-$ol to propene.
$(vi)$ Butan$-2-$one to butan$-2-$ol.

Which of the following alcohols is the most acidic?

Amongst the following compounds,identify which are insoluble,partially soluble,and highly soluble in water:
$(i)$ phenol,$(ii)$ toluene,$(iii)$ formic acid,$(iv)$ ethylene glycol,$(v)$ chloroform,$(vi)$ pentanol.

What is obtained by the reaction of primary and secondary alcohols with red-hot copper?