Which of the following reaction of diazonium salt involves retention of diazonium group?

Which of the following reaction of diazonium salt involves retention of diazonium group?
  1. Reaction with phenol
  2. Reaction with phosphinic acid
  3. Reaction with dilute sulphuric acid
  4. Reaction with HCl and Cu powder

Asked in: MHT CET 2020 (16 Oct Shift 2)

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