How is the presence of nitrogen detected in organic compounds?

Which reagent is commonly used to detect nitrogen in organic compounds using the Dumas method?

Which functional group is primarily responsible for the detection of sulphur in organic compounds using the Silver Nitrate Test?

In the detection of nitrogen in organic compounds, a common test involves the formation of ammonia gas. Which reagent is typically used to carry out this test?

How can sulfur be detected in organic compounds using a chemical test?

Statement 1: Kjeldahl method fails for pyridine.

Statement 2: In Kjeldahl method pyridine is easily converted to ${\mathrm{N}}_2$.