The question requires us to write the products for the reactions given.
a) The first item presents a neutralization reaction between a strong acid (HCl) and base (NaOH). Thus, the product of the reaction will be a salt that is a combination of the anion of the acid (Cl-) and cation of the base (Na+), and water:
HCl + NaOH -> NaCl + H2O
(the reaction produces sodium chloride and water)
b) The second item also brings a reaction between an acid (HF) and a base (NaOH), where the product will be a salt formed from the anion of the acid (F-) and the cation from the base (Na+), and water:
HF + NaOH -> NaF + H2O
(the reaction produces sodium fluoride and water)
c) The third reaction happens between an acid (HI) and an acidic salt (MgSO4). In this case, an acid and a salt will be formed. We can see this reaction as a double displacement, where the cations and anions of each reactant "exchange" places to form two new compounds:
2 HI + MgSO4 -> H2SO4 + MgI2
(the products formed are sulfuric acid and magnesium iodide)