Question

A non-metal A which is the largest constituent of air, when heated with H₂ in 1:3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O₂ it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.

1. Identify A, B, C and D
2. To which group of periodic table does this non-metal belong?

Answer 1

1.  Non-metal A is nitrogen because it is the largest constituent of air which constitute around 78% of the gases, B is ammonia, C is Nitrogen dioxide and D is Nitric acid.
   When heated with H₂ in 1:3 ratio in the presence of a catalyst Fe, the following reaction takes place :
   `"N"_2 + 3"H"_2 -> 2"NH"_3`
   On heating nitrogen with O₂, it gives nitrogen dioxide.
   `"N"_2("g") + 2"O"_2("g") -> 2"NO"_2("g")`
   When nitrogen dioxide is passed into the water in the presence of air it gives nitric acid.
   `4"NO"_2("g") + 2"H"_2"O"("l") + "O"_2("g") -> 4"HNO"_3("aq")`
2. Nitrogen belongs to group 15 of the modern periodic table.