When hydrochloric acid is reacted with zinc heat is released. there is no external energy source such as a flame used, so where does the heat energy come from?

Explanation:

When a chemical reaction happens, the net change of enthalpy of the products and the reactants is the heat of reaction:

Then, when ∑ ΔHproducts > ∑ ΔA reactants, ΔH rxn > 0 and heat is released. This is what is called an exothermic reaction.

In an exothermic reaction, heat is released, ΔH > 0, and the surroundings will get hotter.

In and endothermic reaction heat is absorved, ΔH < 0, and the surroundings will get cooler.

possibly, yes.

explanation:

the amount of sugar you take in is dangerously high, risk of heart disease, high risk of diabetes, and etc.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current