What is the valency of Nitrogen in compound Ammonia?

What is the colour of Nitrogen dioxide?

What is the main source of nitrogen?

What is Valency?

What is variable valency?

What is the importance of nitrogen cycle?

What is the valency of Phosphate (PO_4) ?

For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evoled ammonia was absorbed in 60 mL of M/10 sulphuric acid. The unreacted aicd required 20 mL of M/10 sodium hydroxide for complete neutralisation. The precentage of nitrogen in the compound is-

In the Lassaigne's test for the detection of nitrogen in an compound, the appearance of blue coloured compound is due to-

What is Valency of an element?