Answer: Ca(OH)2 (aq) + H2SO4 (aq) ---------->  CaSO4(aq) + 2H2O(l)
Explanation:
Since this is a neutralization reaction, the end product would be salt and water. In this equation Calcium will displace hydrogen from the acid because it is more reactive, resulting in the formation of CaSO4 (salt), while the displaced H2 molecule combines with OH molecules to form water.
The equation of the reaction is thus;
Ca(OH)2 (aq) + H2SO4 (aq) ---------->  CaSO4(aq) + H2O(l), in other to balance it, we add ''2'' to the water molecule in the right hand side of the equation.
Balance equation is   
Ca(OH)2 (aq) + H2SO4 (aq) ---------->  CaSO4(aq) + 2H2O(l)
 
        
             
        
        
        
The answer should be B: -3
        
             
        
        
        
It depends on what type of graph you have. The easiest would be using a H-T diagram. Enthalpy of vaporization is the physical change from liquid to vapor. It occurs at a constant pressure and a constant temperature. As shown in the picture, 1 point is drawn on the subcooled liquid, and another point of the saturated vapor isothermal line. Now, the difference between those two points is the value for the enthalpy of vaporization of water.
 
        
        
        
The reactants are the substances on the left side, which react and give the products on the right side. 
The reactants are Fe and O.
The product is Fe2O3.
The arrow to the right means that the reaction is going in only one direction — the only reaction happening at the moment is that Fe and O are making Fe2O3.
(s) means the substance is in the solid state, and (g) means in a gaseous state (or the substance is a gas in that reaction).