I get the mass and molar mass part and the equation but not quite sure what the x,y stoechoimetric coeficients are to be honest. Is it the ratio or what and could you tell me what it is for question 4 (so x,y)
For questions like these, it's all about tracking your units. I find that writing out expressions where the units cancel is paramount to getting the question right.
C6H12O6 :rarrow: 2 C2H5OH + 2 CO2
MWsugar = 180 g/mol
MWalcohol = 46 g/mol
[itex]\textrm{2 kg sugar } \times\frac{1000\textrm{ g}}{1\textrm{ kg}}\times\frac{1\textrm{ mol sugar}}{180 \textrm{ g sugar}} \times\frac{2 \textrm{ mol alcohol}}{1 \textrm{ mol sugar}}\times \frac{46 \textrm{ g alcohol}}{1 \textrm{ mol alcohol}}[/itex]
See how in the above expression you can start to cancel out units left to right? If you want to always use grams and moles (rather than kg and kmoles) the first thing you do is convert from kg to g. Then you can convert from grams sugar to moles sugar. Then the (sorta) tricky part of using the stoichiometric coefficients. For every 1 mol of sugar consumed you create 2 moles of alcohol! Then you can convert the moles of alcohol to grams of alcohol, et voilà. You should be left with only the units you care about, which in this case is a mass of alcohol (in grams). I've left out the conversion back to kg if that's the unit you want.
I would set up your problems like this. Include the balanced chemical equation like Hunter2 said. Cancel units. Double check that the units that remain make sense.