Match the transformations in column I with appropriate options in column II

Column I
(A) CO₂(s) $$\to$$ CO₂(g)
(B) CaCO₃(s) $$\to$$ CaO(s) + CO₂(g)
(C) 2H $$\to$$ H₂(g)
(D) P_{(white, solid)} $$\to$$ P_{(red, solid)}

Column II
(p) phase transition
(q) allotropic change
(r) $$\Delta H$$ is positive
(s) $$\Delta S$$ is positive
(t) $$\Delta S$$ is negative

In 1 L saturated solution of AgCl [K_sp(AgCl) = 1.6 $$\times$$ 10^-10], 0.1 mol of CuCl [K_sp(CuCl) = 1.0 $$\times$$ 10^-6] is added. The resultant concentration of Ag⁺ in the solution is 1.6 $$\times$$ 10^-x. The value of "x" is

The number of hexagonal faces that are present in a truncated octahedron is ____________.

The freezing point (in ^oC) of a solution containing 0.1 g of K₃[Fe(CN)₆] (Mol. wt. 329) in 100 g of water (K_f = 1.86 K kg mol^-1) is