For a reaction, `aA+bBhArrcC+dD`, the reaction quotient `Q=([C]_(0)^(c)[D]_(0)^(d))/([A]_(0)^(a)[B]_(0)^(b))`, where `[A]_(0)`, `[B]_(0)`, `[C]_(0)`, `[D]_(0)` are initial concentrations. Also `K_(c)=([C]^(c)[D]^(d))/([A]^(a)[B]^(b))` where `[A]`, `[B]`, `[C]`, `[D]` are equilibrium concentrations. The reaction proceeds in forward direction if `Q lt K_(c)` and in backward direction if `Q gt K_(c)`. The variation of `K_(c)` with temperature is given by: `2303log(K_(C_(2)))/(K_(C_(1)))=(DeltaH)/(R)[(T_(2)-T_(1))/(T_(1)T_(2))]`. For gaseous phase reactions `K_(p)=K_(c)(RT)^(Deltan)` where `Deltan=` moles of gaseous products `-` moles of gaseous reactants. Also `-DeltaG^(@)=2.303RT log_(10)K_(c)`. The equilibrium constants for the reaction, `CaC_(2(s))+5O_(2(g))hArr2CaCO_(3(s))+2CO_(2(g))` is//are given by:A. `K_(c)=([CO_(2)]^(2))/([O_(2)]^(5))`B. `K_(p)=((n_(CO_(2)))^(2))/((n_(O_(2)))^(5))xx[(P)/(sumn]]^(-3)`C. `K_(p)=((p_(CO_(2)))^(2))/((P_(O_(2)))^(5))`D. either of these