Final answer:
The Americans with Disabilities Act (ADA) is the federal law that makes it illegal to give extra duties to just one gender.
Step-by-step explanation:
The federal law that would make it illegal to give extra duties to just one gender is the Americans with Disabilities Act (ADA). The ADA of 1990 prohibits discrimination against individuals with disabilities, including gender-based discrimination. It requires employers of more than fifteen people to make reasonable accommodations for disabled persons. This law ensures that individuals with disabilities are not treated unfairly or given unequal treatment based on their gender.