This answer is correct . There are five types of attributes in database. These are :- 1.) Simple attribute 2.) Composite attribute  3.) Single-valued attribute 4.) Multivalued attribute and 5.) Derived attribute. There is no attribute named Unary. Unary is a type of relation which is known as degree of relation (unary, binary, ternary etc.). So this is the correct answer according to the question.

This is true choice. Q statement is correct because the primary key and the foreign key can exist in the same relation. Moreover foreign key can refer to the primary key in the same relation.So, this is a correct choice.

This answer is correct. Connectivity means how many instances of one entity are associated with how many instances of other entity. Connectivity of a relationship can be classified in 4 types. These are :- 1.) One to one (1 : 1) 2.) One to many (1 : M) 3.) Many to one (M : 1) 4.) Many to many(M : N). So, this answer is correct.

This answer is correct. There is no particular reason to explain this answer, because there is a name convention in DBMS. The members of weak entity set are called subordinate entity set. So, this answer is correct.

This answer is correct. There are 3 types of record based data models. These are :- 1.) Hierarchical model 2.) Network model 3.) Relational model

There are five types of attributes in a database. These are :- 1.) Simple attribute 2.) Composite attribute 3.) Single-valued attribute 4.) Multivalued attribute 5.) Derived attribute

Both the options are correct. So, this choice is correct.

Option P is correct because a candidate key is a key that uniquely identifies a row in a relation. So, this cannot be null as it uniquely identifies a row. Option R is correct because primary key is chosen from a set of candidate keys. In other words all the candidate keys are the candidates for the primary key. So, in this way all the candidate keys are primary keys. So, this is the correct answer.

This answer is correct. There are seven types of keys in a relational database. These are :- 1.) Primary key 2.) Candidate key 3.) Super key 4.) Foreign key 5.) Alternate key 6 .) Artificial key 7.) Composite key So, this answer is correct.

Yes, this is the correct answer. Both  are correct.

This is the correct answer. The entity set that does not have sufficient attributes to form a primary key, and relies on another for its identification,  is called a weak entity set. It does not have a primary key. So, this is correct answer.

All of the given options are true. So, this is the correct choice.

This answer is correct. There are 3 types of data models present in DBMS. These are :- 1.) Object based data model 2.) Record based data model 3.) Physical data model So, this answer is correct.

This answer is correct. There is no particular reason to explain this answer, because there is a name convention in DBMS. The members of strong entity set are called dominant entity set. So, this answer is correct.

This is a correct choice. Statement R is true because we can apply restrictions on values of attributes these are known as constraints. So, this answer is correct.