Answer:
2.37x10⁻⁷ M⁻².s⁻¹
Explanation:
For a generic reversible reaction:
A + B ⇄ C + D
Kf is the constant of the formation of the products (C and D), Kr is the constant of the formation of the reactants (A and B), and Kc is the general equilibrium constant, which is:
Kc = Kf/Kr
2.76x10³ = 6.54x10⁻⁴/Kr
Kr = 6.54x10⁻⁴/2.76x10³
Kr = 2.37x10⁻⁷ M⁻².s⁻¹
Since there is more energy added as heat rises, the particles disperse and have larger movements.
Percent composition by mass is calculated (mass of element within compound)/(mass of compound)*100. The lower the total molar mass of the compound, the greater the percent composition of sulfur. In this case, MgS would be that compound, since Mg has the lowest molar mass of the four elements bonded to S.
Please add a picture of what numbers ; )