In Kjeldahi's method, CuSO4 acts as ________? 

The correct answer is Catalytic agent.Key Points

Kjeldahl’s method:

• This method is used for the estimation of nitrogen.
• The nitrogen-containing compound is treated with concentrated H₂SO₄  to get ammonium sulfate which liberates ammonia on treatment with NaOH, ammonia is absorbed in known volume of standard acid.
• In this method CuSO₄ acts as a catalytic agent.
• Kjeldahl method is not applicable to compounds containing nitrogen in nitro and azo groups and nitrogen present in the ring (e.g. pyridine) as nitrogen of these compounds does not change to ammonium sulphate under these conditions.