Magnesium hydroxide is an ingredient in some antacids. Antacids react with excess hydrochloric
acid in the stomach to relieve indigestion.
Mg(OH)2 +
HCI-> MgCl2 +
a. Balance the reaction of Mg(OH)2 with HCI.
b. Write the mole ratio that would be used to determine
the number of moles of MgCl2 produced when HCI
reacts with Mg(OH)2.
Н,0
Chemistrynline Chapter Test glencoe. com​

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

c, liquids evaporate, creating a gas

what is the question here. i think you messed up.