Hi @simsimjoey, that's a really great question. You can be pretty confident that most constants (gas law constant, rate law constant, Ksp, etc.) will be provided for you on Test Day. There are a few select constants and conversions you should try to memorize, for example Avogadro's number (6.022 x 10^23), the density of water (1 g/cm^3), pi (3.14), the molar volume of gases at STP (22.4 L/mol), standard pressure (1 atm = 760 mmHg), and the conversion between degrees Celsius and Kelvin (0°C = 273 K). I also recommend familiarizing yourself with the equations in Appendix B of your Next Step PCAT Review Book!
Let me know if you have any questions about specific constants - and I hope this answer was helpful. Good luck studying!