For the following reaction, the equilibrium constant K_c at 298 K is 1.6 $$ \times $$ 10¹⁷.

Fe²⁺(aq) + S^2-(aq) ⇌ FeS(s)

When equal volumes of

0.06 M Fe²⁺(aq) and 0.2 M S^{2$$ - $$}(aq)

solutions are mixed, the equilibrium concentration of Fe²⁺(aq) is found by Y $$ \times $$ 10^{$$ - $$17} M. The value of Y is .................

A closed tank has two compartments $$A$$ and $$B,$$ both filled with oxygen (assumed to be ideal gas). The partition separating the two compartments is fixed and is a perfect heat insulator (Figure $$1.$$). If the old partition is replaced by a new partition which can slide and conduct heat but does NOT allow the gas to leak across (Figure $$2$$), the volume (in $${m^3}$$) of the compartment A after the system attains equilibrium is ______________.