Every mole of MgCl2 reacts with 2 moles of KOH, therefore the 4 moles of KOH will only react with 2 moles of MgCl2, making it the limiting reagent and therefore KOH determines how much Mg(OH)2 is produced.
Recycling!! And also planting more trees.
Hope this helps!
Number of moles ( substance x ):
1 mole --------- 58.45 g/mol
? mole --------- 326.0 g
326.0 x 1 / 58.45 => 5.577 moles
heat of fusion:
hf = Cal / moles
hf = 4325.8 Cal / 5.577 moles
hf = 775.65 cal/mol
hope this helps!
The fiction is b because the terms mean subtract