i just don't know where to begin/how

a) Write a balanced chemical equation for: potassium carbonate + magnesium chloride


b) Write a balanced chemical equation for: sulfuric acid + calcium carbonate


c) Write a balanced chemical equation for: sodium sulfate + calcium nitrate


d) Write a balanced chemical equation for: sulfur tetrafluoride + water

2 answers

What's your trouble here. You need to learn to do this yourself. I'll be glad to help you through.
first write just the compounds.

K2CO3 + MgCl = KCl + MgCO3

Note you have 2K on the left, but just one on the right. Fix that:

K2CO3 + MgCl2 = 2KCl + MgCO3

Now things match on both sides

Similarly, you can work your way to

H2SO4 + CaCO3 = CaSO4 + CO2 + H2O
Na2SO4 + Ca(NO3)2 = CaSO4 + 2NaNO3
SF4 + 3H2O = H2SO3 + 4HF