Answer & explanation:
Canned fruits and vegetables generally have a high acidity and salinity content, in order to prevent the product from spoiling, in addition to enhancing its flavor.
The cream-based sauce started to curdle due to the acidity present in the canned tomatoes.
By lowering the pH of dairy products, a protein in them called casein begins to clot. It is this clotting of the casein that causes the cream-based sauce to curdle.
It is called exothermic reaction because it releases heat and light and it is called combustion reaction because it is reacting and is being oxidised by O2 to MgO.
It can also be called as oxidation reaction since Mg is oxidised to MgO.
Reactants would be the missing word in the sentence because they make up the products in a chemical reaction