(i) We start by calculating the mass of sugar in the solution:
mass of sugar = concentration × solution mass
mass of sugar = 2.5/100 × 500 = 12.5 g  
Then now we can calculate the amount of water:
solution mass = mass of sugar + mass of water
mass of water =  solution mass - mass of sugar
mass of water = 500 - 12.5 = 487.5 g
(ii) We use the following reasoning:
If       500 g solution contains 12.5 g sugar
Then    X g solution contains 75 g sugar
X=(500×75)/12.5 = 3000 g solution
Now to get the amount of solution in liters we use density (we assume that is equal to 1):
Density = mass / volume
Volume = mass / density
Volume = 3000 / 1 = 3000 liters of sugar solution
 
        
             
        
        
        
The answer is D because it sounds like the most ethical answer. The other choices are wrong because the could possibly hurt someone or an animal.
        
                    
             
        
        
        
The reaction between calcium carbonate and hydrochloric acid can be expressed through the chemical reaction,
    CaCO3 + 2HCl --> CaCl2 + H2O + CO2
The molecular weight of calcium carbonate is 100 g/mol while that of hydrochloric acid is 36.45. The equation above depicts that 100 g of calcium carbonate can be dissolved in 72.9 g of hydrochloric acid. 
    x = (4 g HCl)(100 g CaCO3 / 72.9 HCl)
      x = 5.49 g
Answer: 5.49 g
        
                    
             
        
        
        
The balanced reaction for combustion is as follows ;
2C₂H₅OH + 6O₂ ---> 4CO₂ + 6H₂O
the stoichiometry of C₂H₅OH to O₂ is 2:6
that means 2 mol of C₂H₅OH reacts with 6 mol of O₂.
when 1 mol of C₂H₅OH reacts with 6/2 mol of O₂,
then 0.3020 mol of C₂H₅OH reacts with - 6/2 x 0.3020
therefore number of O₂ moles reacted = 0.91 mol