Please help me answer these questions related to databases. Also, provide an explanation for your answer.

1. When would it be wise to specify the role played by an entity in a relationship? a) when the same entity set participates more than once in the relationship set, b) when the . relationship is ternary, or c) when the entity represents an abstract rather than physical thing ______

2. In an ER model, would it be possible for the same two entity sets to participate in two different relationship sets? (yes/no) _________

3. It is possible for a attribute to be multivalued in a ___________________ but not a _________________. (Fill in the blanks to get the best possible answer that can be formed using the terms ER model, relational schema, and recursive relationship.)

4. Why might you want to model address as a composite attribute (built from attributes street, city, state, and zip, perhaps) rather than just using all of the individual attributes? Would it be a) because in the model we might want to sometimes refer to the address as a whole and sometimes to parts of the address, b) to save space, or c) to avoid possible null values ______

5. Why might it be a bad idea to model the name of an instructors department as an attribute of the instructor? Would it be because: a) we might in the future want to allow instructors to belong to multiple departments, b) it is important to model the smallest possible number of attributes, or c) department names can change? (select all that apply) _________