there weren't any mole questions when i took it. know your conversions for math!!! (like oz to lbs and such). there were plenty of those. otherwise the math was very basic. addition/sub mult/divide whole numbers/fractions/ratios. if you take all of the practice tests you should be fine. chemistry was basic. i remember being asking about properties of water, reactions types, organic vs inorganic. read the biology section of the A2 study guide even if you don't take that test - there is material from this section that is asked about in the chemistry portion of the Hesi!