Question The minimum size of placards identifying hazardous materials is: Answers Four inches. Six and one-quarter inches. Nine and three-quarter inches. 10 and three-quarter inches. Explanation Hazardous materials placards must be at least 10 and three-quarter inches square. This questions appears in the following tests: Colorado Class A Knowledge Test Georgia Tank Illinois Class A Knowledge Test Illinois Class B Knowledge Test Illinois Passenger Kansas Class B Knowledge Test Nebraska Class B Knowledge Test Nevada Double New York Class B Knowledge Test South Carolina Class B Knowledge Test Tennessee Class B Knowledge Test Wyoming Class A Knowledge Test Wyoming Passenger