I live in Mississippi. I am taking my HAZMAT test tomorrow. If anyone can help with these 2 questions.

Number of Placards: In MS CDL manual it doesn't state how many. In class and video we were told there are 19 placards. Practice test I took it was 31. Anyone know the correct number???

Number of years before recertified: In video we were told 2 years, in MS CDL manual it states 3 years. One of the practice test it said 2 years. Anyone know correct answer.

Thanks for any input on these questions.