How the two modes work
Quiz mode — you pick an answer, it tells you right away if you were right. If you got it wrong it shows you the correct answer and why.
Study mode — every question with the correct answer already highlighted in green, so you can read straight through and memorise.
About the answers
The original PDFs had no answer key, so the answers here were worked out from the CARs, the TC AIM and From the Ground Up, then independently double-checked.
chart means the question refers to a VNC, METAR/TAF, weight-and-balance graph or table that wasn't in the PDFs — treat that answer as a best guess.
check means the wording is ambiguous and worth confirming with your instructor.