Determine how IR spectroscopy can be used to confirm that the following reaction has been completed. Also, how could you confirm that all of the NH₂—NH₂ was removed after purification?

• A. Absence of the absorption band at 1700 cm⁻¹ would confirm the completion of the reaction. And absence of the absorption band at 3400 cm⁻¹ would confirm the removal of NH₂¬NH₂.
• B. Absence of the absorption band at 3100 cm⁻¹ would confirm the completion of the reaction. And presence of the absorption band at 2900 cm⁻¹ would confirm the removal of NH₂¬NH₂.
• C. Presence of the absorption band at 1700 cm⁻¹ would confirm the completion of the reaction. And absence of the absorption band at 3400 cm⁻¹ would confirm the removal of NH₂¬NH₂.
• D. Presence of the absorption band at 3100 cm⁻¹ would confirm the completion of the reaction. And presence of the absorption band at 2900 cm⁻¹ would confirm the removal of NH₂¬NH₂.

Answer: (A)