Aryl fluoride can be obtained directly by heating which arenediazonium salt?

Benzenediazonium fluoroborate

The correct answer is option 2. Benzenediazonium fluoroborate.

Fluorobenzene can be obtained from benzene diazonium chloride by using Balz–Schiemann reaction. In this reaction an aromatic amine is converted into an aryl fluoride via a diazonium tetrafluoroborate intermediate. This method is used commonly to obtain Fluorobenzene and its derivatives.

The conversion happens as follows: Aniline is treated with nitrous acid to form benzene diazonium chloride, further on reaction with \(HBF_4\) to give benzene diazonium fluoroborate. On further heating it undergoes decomposition to give fluorobenzene. The reaction is shown below:

Derivatives like 4-fluorobenzoic acid are also obtained by this method.