6- it's based on a collection of objects a. The network model b. The physical model c. The object oriented model 7. The actual data stored in a database at a particular moment in time a. Database schema b. Database instance e. Database independesce. 8. Used to specify DB retrievals, insertion, deletion, and modification of the data. a. DDL. b. SDL c. DML 9. Precompiler a. Used to compile DML b. Used to compile the host language c. Used to separate between the DML and the hont language 10. Attribute a. Row b. Column header c. Populated table 11. The primary key atributes PK of each relation scbema R in 5 canwea have: null values in any tuple of r(R). a. Entity integrity constrain b. Kcy constrain c. Referential integrity constrain 12- A constraint involving two relations a. Entity integrity constrain b. Key constrain c. Referential integrity constrain The primary key value is used to uniquely identify each tuple in a relation 13. a. Entity integrity constrain b. Key constrain c. Referential integrity constrain