A. It must be testable in order to be found true or false.
helium, beryllium, magnesium, calcium, strontium, barium, radium. i believe any of these are proper answers.
For the first question, the correct answer would be 44.51 kJ. It is calculated by multiplying the amount of the substance in moles by the heat of the solution. For the second question, the correct answer would be a catalyst causes <span>a lowering the activation energy barrier.</span>
Answer is: <span> the equilibrium concentration of Br</span>₂ is 0,02 mol/L.<span>
</span>Chemical reaction: Br₂ + Cl₂ → 2BrCl.
Kc = 7,0.
c₀(Br₂) = 0,25 mol ÷ 3 L.
c₀(Br₂) = 0,083 mol/L.
c₀(Cl₂) = 0,55 mol ÷ 3 L.
c₀(Cl₂) = 0,183 mol/L.
Kc = c(BrCl)² ÷ c(Br₂) · c(Cl₂).
7 = (2x)² ÷ (0,083 mol/L - x) · (0,183 mol/L - x).
7 = 4x² ÷ (0,083 mol/L - x) · (0,183 mol/L - x).
Solve q<span>uadratic equation: x = 0,063 mol/L.
</span>c(Br₂) = 0,083 mol/L - 0,063 mol/L = 0,02 mol/L.
