From the following data, the heat of formation of Ca(OH)_2(s) at 18°C is ………..kcal:

Which of the following statement(s) is/are correct :

Statement(a) : Δ_rH° for the reaction H₂O(g) → 2H(g) + O(g) is 925 kJ/mol

Statement(b) : Δ_rH° for the reaction OH(g) → H(g) + O(g) is 502 kJ/mol

Statement(c) : Enthalpy of formation of H(g) is-–218 kJ/mol

Statement(d) : Enthalpy of formation of OH(g) is 42 kJ/mol

The pressure-volume work for an ideal gas can be calculated by using the expression  The work can also be calculated from the pV– plot by using the area under the curve within the specified limits. When an ideal gas is compressed (a) reversibly or (b) irreversibly from volume Vi to Vf . choose the correct option.

During complete combustion of one mole of butane, 2658 kJ of heat is released. The thermochemical reaction for above change is Δ_fU⁰ of formation of CH₄ (g) at certain temperature is –393 kJ mol⁻¹. The value of Δ_fH⁰is

Calculate the standard enthalpy of formation of CH₃OH(l) from the following data: 

CH_3​OH(I)+3/2​O₂​(g)→CO₂​(g)+2H₂​O(l);  △_r​H^θ=−726kJmol⁻¹

C_(graphite)​+O₂​(g)→CO₂​(g);    △_c​H^θ=−393kJmol⁻¹

H_2​(g)+1/2​O₂​(g)→H₂​O(l);    △_f​H^θ=−286kJmol⁻¹

Suppose the elements X and Y combine to form two compounds XY₂ and X₃Y₂. When 0.1 mole of XY₂ weighs 10 g and 0.05 mole of X₃Y₂ weighs 9 g, the atomic weights of X and Y are

For an endothermic reaction when ΔH represents the enthalpy of the reaction in kJ mol^-1, the minimum value for the energy of activation will be

Enthalpies of formation of CO(g) , CO₂ (g) , N₂O (g) and N₂O₄ (g) are -110, - 393, 81 and 9.7 kJ mol^-1. Thus, Δ_rU for the reaction at 298 K is,

The equilibrium concentrations of the species in the reaction A + B ⇔ C + D are 2, 3, 10 and 6 mol L^-1, respectively at 300 K. ΔG⁰ for the reaction is (R = 2cal/mol K)