Biochemical oxygen demand (BOD) is a measure of organic materials present in water, BOD value less than 5 ppm indicates a water sample to be

Sodium fusion extract of aniline when heated with ferrous sulphate solution and then acidified with concentrated $\mathrm{H}_2 \mathrm{SO}_4$ from which of the following complexes?

Ethyl phenyl acetylene (1-phenyl-1-butyne) on reduction with partially deactiveated palladised charcoal (Lindlar's catalyst) gives

Which one of the following methods is suitable to generate aromatic compound(s) from linear aliphatic saturated hydrocarbons with at least six carbon atoms?