For the reaction

Fe₂N(s) + $${3 \over 2}$$H₂(g) ⇌ 2Fe(s) + NH₃(g)

A solution of two components containing n₁ moles of the 1^st component and n₂ moles of the 2^nd component is prepared. M₁ and M₂ are the molecular weights of component 1 and 2 respectively. If d is the density of the solution in g mL^–1, C₂ is the molarity and x₂ is the mole fraction of the 2^nd component, then C₂ can be expressed as :

The increasing order of pK_b values of the following compounds is :

The area (in sq. units) of the region
A = {(x, y) : |x| + |y| $$ \le $$ 1, 2y² $$ \ge $$ |x|}