Which hazard classes become unstable and dangerous when wet, and must be kept dry?

Class 4 (Flammable Solids) and Class 5 (Oxidizers). Section 9.4: Class 4 and 5 materials, which become unstable and dangerous when wet,

Which hazard classes become unstable and dangerous when wet, and must be kept dry?

ANSWER BREAKDOWN
  • A. Incorrect. "Class 2 and Class 3" is not correct. Class 4 and 5 materials, which become unstable and dangerous when wet, must be kept dry while in transit.
  • B. Correct. Class 4 and 5 materials, which become unstable and dangerous when wet, must be kept dry while in transit.
  • C. Incorrect. "Class 6 and Class 8" is not correct. Class 4 and 5 materials, which become unstable and dangerous when wet, must be kept dry while in transit.
  • D. Incorrect. "Class 9" is not correct. Class 4 and 5 materials, which become unstable and dangerous when wet, must be kept dry while in transit.