The statement that is NOT correct is

• A

  In solid state \( \mathrm{PCl}_{5} \) exists as \( \left[\mathrm{PCl}_{4}\right]^{+}\left[\mathrm{PCl}_{6}\right] \)
• Correct answer
  B

  Phosphorous acid on heating disproportionate to give meta phosphoric acid and
  phosphine.
• C

  Hypo-phosphorous acid reduces silver nitrate to silver.
• D

  Pure phosphine is non-inflammable,

Hence, the correct answer is option: 'B'.