for the first question
BaCO3 + 2HCl -----------> BaCl2 + CO2 +H2O
this is because it is a double replacement as well as a neutralization reaction
Can you please explain this more? I get the double displacement part, but not the neutralization! is BaCO3 a base or something?
for the second question
c and d are incorrect because the charges have to cancel out and if you add up the charges in each of the answer choices, they do not cancel out in choices c and d
hope this helps