Hi I've got a couple of thoughts on this we have written minus X is there any reason why you've written this or is this just like you've just picked it up from somewhere I'm asking this that if there's a negative sign that means that the reaction is in exothermic what are the negative sign imply it implies that your final energy is lower than your initial energy right and the difference in energy is released as heat of what energy of reactants energy of products energy of products are lower than that of reactants hence it's negative figure you're asking for mole of what so it's an awesome question right it's usually per mole of some definition out there like say Delta H not F that means that you're forming one mole of product and from its standard states then you have Delta H of combustion so you are burning one mole of something that is what per mole means now if you're going to be like a hey what if you have some random reaction per mole of what that is where things get a little complicated and that is what your teacher answered