Answer:
4.3 moles of Fe2O3
Explanation: 
The calculations are shown in the picture.
 
        
             
        
        
        
The percent by mass of calcium hydroxide in the solution : 15.41%
<h3>Further explanation</h3>
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight/volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
Mass of solute (Ca(OH₂-Calcium hydroxide) : 28.5
Mass of solution = 185 g

 
        
             
        
        
        
Answer:
ΔS° = -268.13 J/K
Explanation:
Let's consider the following balanced equation.
3 NO₂(g) + H₂O(l) → 2 HNO₃(l) + NO(g)
We can calculate the standard entropy change of a reaction (ΔS°) using the following expression:
ΔS° = ∑np.Sp° - ∑nr.Sr°
where,
ni are the moles of reactants and products
Si are the standard molar entropies of reactants and products
ΔS° = [2 mol × S°(HNO₃(l)) + 1 mol × S°(NO(g))] - [3 mol × S°(NO₂(g)) + 1 mol × S°(H₂O(l))]
ΔS° = [2 mol × 155.6 J/K.mol + 1 mol × 210.76 J/K.mol] - [3 mol × 240.06 J/K.mol + 1 mol × 69.91 J/k.mol]
ΔS° = -268.13 J/K
 
        
             
        
        
        
Answer:
not sure about 6 but 7 should be c
Explanation:
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Step 1: write the equation:
                                          P₄(s) + 6F₂(g) → 4PF₃(g) 
Step 2: Molar mass of P₄ = 30.97 g/mol × 4 = 123.88 g/mol
Step 3: Number of moles of phosphorus
                                                    n = m/M 
                                                    n = 8.5 g/123.88g/mol
                                                    n = 0.07 moles
Step 4: 0.07 × 12 = 0.84 moles of fluorine.
Fluorine is diatomic gas so we multiplied the number of moles by 12.
Step 5: To find the mass of fluorine we multiply the number of moles with the molar mass.
                            Mass of fluorine = 0.84 ×  228 
                                                        = 191.52 grams.