Inheritance

Question 1

What is an abstract class?

A) A class with no methods
B) A class with at least one abstract method, intended as a base class
C) A fully implemented class with complete methods
D) A class that can be instantiated directly

Answer 1

Correct Answer: B

Question 3

Why can’t you instantiate an abstract class?

A) It is fully defined and meant for creating objects
B) It is incomplete and meant only to provide a base for other classes
C) It has private constructors
D) It lacks access modifiers

Answer 3

Correct Answer: B

Question 4

What is required for a class to be considered abstract?

A) It must have at least one abstract method
B) It must be instantiated directly
C) It must inherit another class
D) It must not contain any methods

Answer 4

Correct Answer: A

Question 5

What keyword is used to declare an abstract method?

A) virtual
B) override
C) abstract
D) protected

Answer 5

Correct Answer: C

Question 6

What does an abstract method NOT include?

A) Method signature
B) Access modifiers
C) Code implementation
D) Parameters

Answer 6

Correct Answer: C

Question 7

What is the purpose of an abstract class in object-oriented programming?

A) To define exact details for all subclasses
B) To provide a common blueprint that subclasses can implement
C) To avoid inheritance
D) To allow for multiple instantiation

Answer 7

Correct Answer: B

Question 8

Where are abstract classes typically found in a class hierarchy?

A) At the bottom level
B) Only in middle levels
C) Often at the top as base classes
D) Only as interfaces

Answer 8

Correct Answer: C

Question 9

In terms of hierarchy, what does aggregation resemble?

A) A linear structure
B) A tree with parent-child relationships
C) A graph with flexible connections
D) A single path structure

Answer 9

Correct Answer: B

Question 10

Which of the following best describes a graph in object organization?

A) A strict parent-child relationship
B) Connections where objects link freely without a set structure
C) A hierarchy where each object has only one parent
D) A single top-level parent and multiple children

Answer 10

Correct Answer: B

Question 11

What is an interface?

A) A class with private fields
B) A structure providing complete code for subclasses
C) A contract specifying required methods and properties
D) A type of static class

Answer 11

Correct Answer: C

Question 12

Which of the following cannot be included in an interface?

A) Method declarations
B) Field variables
C) Event declarations
D) Property declarations

Answer 12

Correct Answer: B

Question 13

What is true about the members of an interface?

A) They can have private access modifiers
B) They are all public by default
C) They can contain member variables
D) They include full implementations

Answer 13

Correct Answer: B

Question 14

What level of abstraction does an interface provide?

A) Partial abstraction
B) No abstraction
C) Full abstraction
D) Limited abstraction

Answer 14

Correct Answer: C

Question 15

Which of the following best describes multiple inheritance in C#?

A) Only interfaces support multiple inheritance
B) Both abstract classes and interfaces support it
C) Only abstract classes support it
D) It is not possible with either

Answer 15

Correct Answer: A

Question 16

What member types can an abstract class include that an interface cannot?

A) Events
B) Properties
C) Field variables
D) Method declarations

Answer 16

Correct Answer: C

Question 17

How many interfaces can a class implement in C#?

A) Only one
B) Up to five
C) Unlimited number
D) None, as C# does not support interfaces

Answer 17

Correct Answer: C

Question 18

What can an abstract class in C# include that an interface cannot?

A) Public method declarations
B) Method implementations
C) Event declarations
D) Property declarations

Answer 18

Correct Answer: B

Question 19

Which access modifiers are allowed in an abstract class?

A) Only public and private
B) All standard access modifiers like public, protected, etc.
C) None
D) Only protected and internal

Answer 19

Correct Answer: B

Question 20

In what way is an interface similar to a contract?

A) It specifies methods that must be implemented by any class using the interface
B) It provides default method implementations
C) It restricts method access based on access modifiers
D) It allows inheritance from multiple classes

Answer 20

Correct Answer: A

Question 20

Which keyword cannot be used with interface members in C#?

A) public
B) private
C) abstract
D) static

Answer 20

Correct Answer: B

Question 21

Why is an abstract class considered a partial abstraction?

A) It does not allow method implementation
B) It can have both implemented and unimplemented methods
C) It only includes abstract methods
D) It cannot be inherited

Answer 21

Correct Answer: B

Question 22

Which of the following statements about interfaces is true?

A) They can inherit from multiple classes
B) They provide method implementation
C) They only define method signatures
D) They are instantiated directly

Answer 22

Correct Answer: C

Question 23

What is the purpose of abstract methods in an abstract class?

A) To provide full implementation of a method
B) To define required methods that subclasses must implement
C) To prevent method overriding
D) To allow multiple instances of the abstract class

Answer 23

Correct Answer: B

Question 24

Which of these relationships is an example of an association in object design?

A) A library and its books where each book belongs to one library
B) A teacher and student where each can exist independently
C) A house and its rooms where rooms cannot exist independently
D) A car and its wheels where wheels cannot exist independently

Answer 24

Correct Answer: B

Question 25

How does the structure of a hierarchy differ from a graph in object-oriented design?

A) A hierarchy has flexible connections; a graph has a strict structure
B) A hierarchy has clear parent-child relationships; a graph has flexible, unrestricted connections
C) Both have unrestricted, flexible connections
D) Both have strictly enforced parent-child relationships

Answer 25

Correct Answer: B