Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Three many families are known quarks divided into.
How many families are known quarks divided into?

Opaque is the term for matter that does not let any light pass through.
What is the term for matter that does not let any light pass through?

Solid is characterized by molecules with minimal movement and strong forces between them.
Which state of matter is characterized by molecules with minimal movement and strong forces between them?