 11. What action does ⋈ operator perform in relational algebra a. Output specified attributes from all rows of the input relation and remove duplicate tuples from the output b. Outputs pairs of rows from the two input relations that have the same value on all attributes that have the same name c. Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes) d. Return rows of the input relation that satisfy the predicate
 Answer: (a).Output specified attributes from all rows of the input relation and remove duplicate tuples from the output

 12. What does the “x” operator do in relational algebra? a. Output specified attributes from all rows of the input relation. Remove duplicate tuples from the output b. Output pairs of rows from the two input relations that have the same value on all attributes that have the same name c. Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes) d. Returns the rows of the input relation that satisfy the predicate
 Answer: (c).Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes)

 13. An attribute is a __________ in a relation. a. Row b. Column c. Value d. Tuple

 14. What is the method of specifying a primary key in a schema description? a. By writing it in bold letters b. By underlining it using a dashed line c. By writing it in capital letters d. By underlining it using a bold line
 Answer: (d).By underlining it using a bold line

 15. Statement 1: A tuple is a row in a relationStatement 2: Existence of multiple foreign keys in a same relation is possible a. Both the statements are true b. Statement 1 is correct but Statement 2 is false c. Statement 1 is false but Statement 2 is correct d. Both the statements are false
 Answer: (a).Both the statements are true

 16. Choose the option that correctly explains in words, the function of the following relational algebra expression:σyear≥2009 (book ⋈ borrow) a. Selects all tuples from the Cartesian product of book and borrow b. Selects all the tuples from the natural join of book and borrow wherever the year is lesser than 2009 c. Selects all the tuples from the natural join of book and student wherever the year is greater than or equal to 2009 d. Selects all tuples from the Cartesian product of book and borrow wherever the year is greater than or equal to 2009
 Answer: (b).Selects all the tuples from the natural join of book and borrow wherever the year is lesser than 2009

 17. State true or false: If a relation consists of a foreign key, then it is called a referenced relation of the foreign key dependency. a. True b. False c. May be d. Can't say