<p>I’ve taken pretty much every test there is for chem, except the latest college board released test. In order of decreasing difficulty:</p>
<ol>
<li>Barrons</li>
<li>Sparknotes / Kaplan (I think they’re about the same level of difficulty)</li>
<li>Released 1994 test</li>
<li>Princeton Review</li>
</ol>
<p>Basically, some people are saying that sparknotes is hardest, while other people are saying that barrons is the hardest. Everyone agrees that PR and Kaplan are the easiest, and Collegeboard ranks above them. </p>