Final answer:
The Department of Homeland Security is the federal organization that responds to and coordinates large hazardous materials incidents.
Step-by-step explanation:
The federal organization that responds to and acts as the coordinating agency on large hazardous materials incidents is the Department of Homeland Security.
After the attacks on 9/11, the Department of Homeland Security was created to oversee various programs and agencies involved in protecting the United States from threats. This department plays a crucial role in responding to hazardous materials incidents and coordinating efforts among federal, state, and local agencies.
The Department of Homeland Security also includes FEMA (Federal Emergency Management Agency) which is responsible for managing and responding to disasters and emergencies, including hazardous materials incidents.