Which premitive unit cell has unequal edge lengths (a $$ \ne $$ b $$ \ne $$ c) and all axial angles different from 90^o?

The metal used for marking X–ray tube window is :

The electronegativity of aluminium is similar to :

The values of K_p/K_c for the following reactions at 300 K are, respectively : (At 300 K, RT = 24.62 dm³ atm mol^–1)

N₂(g) + O₂(g)  $$\rightleftharpoons$$ 2 NO(g)

N₂O₄(g)  $$\rightleftharpoons$$   2 NO(g)

N₂(g) + 3H₂(g) $$\rightleftharpoons$$ 2 NH₃(g)