A pure substance that cannot be separated into simpler substances by physical or chemical means. A pure substance composed of two or more elements that are chemically combined.
First, we write the reaction for CH3OH combustion
CH3OH+3/2O2--->CO2+2H2O
for 1 mole of methanol, we get 1 mole of CO2, therefore for 5,25 moles of methanol we will get 5,25 moles of CO2
One mole represents 6.022∙1023 separate entities, just like one dozen represents 12 objects. So, if there are 6.022∙1023 H2O molecules, that is the same as one mole of water.