Object in Object Oriented Programming (OOPs) MCQ Questions and Answers

1. In Object-Oriented Programming, an object is best described as:
A) A function performing a specific task
B) A self-contained unit consisting of data and methods
C) A library containing multiple functions
D) A syntax rule for defining a class
Answer: B)

2. Which of the following represents the state of an object?
A) Methods
B) Constructors
C) Data members or attributes
D) Return types
Answer: C)

3. The behavior of an object in OOP is defined by its:
A) Variables
B) Methods
C) Class name
D) Access specifiers
Answer: B)

4. In OOP, an object is created from a:
A) File
B) Class
C) Function
D) Pointer
Answer: B)

5. When an object is created, what actually happens in memory?
A) A new class is defined
B) A reference to class is deleted
C) Memory is allocated for instance variables
D) The compiler ignores the object creation
Answer: C)

6. What term describes multiple objects of the same class having different data values?
A) Polymorphism
B) Object variability
C) Instance individuality
D) Data encapsulation
Answer: C)

7. Which keyword in C++ is used to create an object dynamically?
A) malloc
B) create
C) new
D) allocate
Answer: C)

8. In Java, what happens when an object reference is set to null?
A) It points to a random memory location
B) It causes immediate memory release
C) It loses connection to the object instance
D) It becomes a primitive variable
Answer: C)

9. Which among the following is not an essential property of an object?
A) State
B) Behavior
C) Identity
D) Function overloading
Answer: D)

10. The process of hiding internal object details and exposing only necessary parts is known as:
A) Polymorphism
B) Encapsulation
C) Abstraction
D) Inheritance
Answer: B)

11. In OOP, two objects are considered identical if they share the same:
A) Data members
B) Reference or memory address
C) Class name
D) Constructor name
Answer: B)

12. Which operation allows one object to be initialized using another object of the same class?
A) Object migration
B) Copy construction
C) Operator overloading
D) Friend function
Answer: B)

13. When an object goes out of scope, what is typically invoked automatically?
A) Destructor
B) Constructor
C) Copy constructor
D) Friend function
Answer: A)

14. Which of the following statements is true about an object in memory?
A) Objects share a single copy of all variables
B) Each object has its own instance variables
C) Object variables are static by default
D) Objects cannot have private members
Answer: B)

15. What is the default access level of members in a class in C++?
A) Public
B) Private
C) Protected
D) Global
Answer: B)

16. Which of the following is an example of a real-world object?
A) int variable
B) Car
C) if statement
D) Function call
Answer: B)

17. What does the this pointer in C++ refer to?
A) A static variable
B) The current object instance
C) The base class
D) A temporary object
Answer: B)

18. Objects can be passed to functions in C++:
A) By value only
B) By pointer only
C) By value, reference, or pointer
D) By constant only
Answer: C)

19. Which of these is responsible for initializing an object?
A) Destructor
B) Method
C) Constructor
D) Friend function
Answer: C)

20. When multiple objects share the same method name but perform differently, it is called:
A) Inheritance
B) Polymorphism
C) Data hiding
D) Overriding
Answer: B)

21. An object without any reference in memory is eligible for:
A) Compilation
B) Garbage collection
C) Linking
D) Overloading
Answer: B)

22. In Python, every variable that stores data is essentially a/an:
A) Primitive
B) Object
C) Function
D) Instance method
Answer: B)

23. The identity of an object is typically represented by:
A) Class name
B) Method name
C) Memory address or reference
D) Static variable
Answer: C)

24. The term “instantiation” in OOP means:
A) Declaring a class
B) Creating an object from a class
C) Defining a function
D) Compiling a file
Answer: B)

25. What allows objects of different classes to be treated uniformly as objects of a common superclass?
A) Polymorphism
B) Encapsulation
C) Overloading
D) Data abstraction
Answer: A)

26. Which of the following statements about an object is true?
A) It cannot call its own methods
B) It can access its data and methods through the ‘this’ keyword
C) It must always be static
D) It cannot be passed as an argument
Answer: B)

27. Objects that exist for the entire lifetime of a program are usually declared as:
A) Local objects
B) Static objects
C) Temporary objects
D) Dynamic objects
Answer: B)

28. Which of the following is not a characteristic of an object?
A) Identity
B) Behavior
C) State
D) Abstraction level
Answer: D)

29. An object can access another object’s private data only through:
A) Static methods
B) Public or friend methods
C) Global functions
D) Protected inheritance
Answer: B)

30. When two objects share data or communicate, it is known as:
A) Data encapsulation
B) Object interaction
C) Message abstraction
D) Object inheritance
Answer: B)

31. Which method is automatically called when an object is created in Java?
A) finalize()
B) init()
C) Constructor
D) start()
Answer: C)

32. What keyword in Java is used to refer to the current object?
A) self
B) me
C) current
D) this
Answer: D)

33. What happens if an object is created but not referenced in Java?
A) It causes a runtime error
B) It remains permanently in memory
C) It becomes eligible for garbage collection
D) It is converted to a static object
Answer: C)

34. In Python, every class is derived from which built-in class by default?
A) data
B) meta
C) object
D) root
Answer: C)

35. The process of creating a copy of an existing object is known as:
A) Object transfer
B) Object reflection
C) Object cloning
D) Object referencing
Answer: C)

36. Which method in Java is used to compare two objects for equality?
A) compareTo()
B) equals()
C) check()
D) verify()
Answer: B)

37. In C++, which operator is used to access members of an object through a pointer?
A) . (dot)
B) * (asterisk)
C) & (ampersand)
D) -> (arrow)
Answer: D)

38. Which of the following is true about object composition?
A) It replaces inheritance completely
B) It uses objects as parts of another object
C) It models “has-a” relationship
D) It is the same as polymorphism
Answer: C)

39. The keyword “delete” in C++ is used to:
A) Destroy a class
B) Deallocate memory of an object created dynamically
C) Remove a method
D) Clear a namespace
Answer: B)

40. Objects in OOP communicate primarily through:
A) Shared variables
B) Static functions
C) Message passing (method calls)
D) Macros
Answer: C)

41. Which of the following cannot be used to create an object in Java?
A) new operator
B) newInstance() method
C) clone() method
D) delete operator
Answer: D)

42. In OOP, when one object contains another object as a member, it’s called:
A) Inheritance
B) Containment or Composition
C) Polymorphism
D) Encapsulation
Answer: B)

43. Which among these is the opposite of object instantiation?
A) Overloading
B) Object destruction
C) Overriding
D) Constructor chaining
Answer: B)

44. The lifetime of a local object in a function ends when:
A) The function is overloaded
B) The function exits
C) The compiler finishes linking
D) The program restarts
Answer: B)

45. Objects that are part of another object and get destroyed automatically with it are called:
A) Friend objects
B) Static objects
C) Contained objects
D) Transient objects
Answer: C)

46. Which term best describes the relationship between a class and its object?
A) “Has-a”
B) “Is-an-instance-of”
C) “Is-a”
D) “Belongs-to”
Answer: B)

47. If two references point to the same object, changing one affects the other because:
A) They share the same class
B) They point to the same memory address
C) They have identical data
D) They are both static
Answer: B)

48. When a temporary unnamed object is created during expression evaluation, it’s called:
A) Static object
B) Null object
C) Anonymous object
D) Transient object
Answer: C)

49. Which function is called automatically when an object is destroyed in C++?
A) finalize()
B) reset()
C) Destructor
D) clear()
Answer: C)

50. Which of the following cannot exist without a class in OOP?
A) Function
B) Variable
C) Object
D) Constant
Answer: C)

51. An object’s behavior is implemented through:
A) Attributes
B) Methods
C) Constructors
D) Comments
Answer: B)

52. An object in OOP can be uniquely identified by its:
A) Class name
B) Package
C) Identity (memory address)
D) Return type
Answer: C)

53. The relationship between a class and its objects is similar to:
A) Blueprint and house
B) Parent and child
C) File and folder
D) Data and algorithm
Answer: A)

54. Which of the following best defines encapsulation?
A) Combining methods
B) Binding data and functions together inside an object
C) Inheriting base class features
D) Polymorphic behavior
Answer: B)

55. Which of the following statements about objects is false?
A) Objects can interact with other objects
B) Each object can have unique data
C) Objects cannot contain other objects
D) Objects are instances of a class
Answer: C)

56. Which mechanism allows an object to use the same method name but perform differently?
A) Polymorphism
B) Encapsulation
C) Abstraction
D) Association
Answer: A)

57. In Java, object equality by reference is checked using:
A) equals()
B) == operator
C) compareTo()
D) compare()
Answer: B)

58. Which of these is not an example of object instantiation?
A) new Car();
B) Car c = new Car();
C) Car c;
D) Car c = CarFactory.create();
Answer: C)

59. Objects help in achieving which of the following software goals?
A) Reducing abstraction
B) Modularity and reusability
C) Code duplication
D) Data exposure
Answer: B)

60. Which type of object exists only temporarily during a function call?
A) Static object
B) Global object
C) Automatic object
D) Persistent object
Answer: C)

61. Which of the following represents data abstraction in an object?
A) Hiding the internal details of object data representation
B) Providing more variables
C) Overloading functions
D) Using global data
Answer: A)

62. When an object is passed by reference, modifications affect:
A) A copy of the object
B) The original object
C) Only local variables
D) None
Answer: B)

63. Which concept ensures that objects remain valid only within defined contexts?
A) Encapsulation
B) Lifetime management
C) Association
D) Inheritance
Answer: B)

64. Objects that exist independently of any other object are called:
A) Contained objects
B) Friend objects
C) Standalone objects
D) Transient objects
Answer: C)

65. What is the output of creating multiple objects from the same class?
A) Multiple classes
B) Multiple instances with unique states
C) One shared instance
D) Static data only
Answer: B)

66. Which kind of relationship is represented when an object owns another object’s lifecycle?
A) Aggregation
B) Composition
C) Association
D) Encapsulation
Answer: B)

67. What is required for an object to call another object’s method?
A) Global access
B) A valid reference to that object
C) Same class type
D) Static declaration
Answer: B)

68. When all objects of a class share a variable, it is declared as:
A) Local variable
B) Static variable
C) Instance variable
D) Constant
Answer: B)

69. Which kind of object cannot be directly instantiated?
A) Concrete object
B) Abstract class object
C) Static object
D) Private object
Answer: B)

70. When an object contains a reference to another object, it’s known as:
A) Object cloning
B) Object composition
C) Object polymorphism
D) Object serialization
Answer: B)

71. Which of the following describes an object’s state?
A) The class structure
B) The current values of its data members
C) The return type of its functions
D) The order of method calls
Answer: B)

72. The use of multiple objects to represent real-world entities in code primarily supports:
A) Modeling and abstraction
B) Code obfuscation
C) Static analysis
D) Debugging
Answer: A)

73. A class that cannot create objects directly but defines behavior for subclasses is called:
A) Concrete class
B) Abstract class
C) Static class
D) Derived class
Answer: B)

74. Which mechanism allows an object to maintain its state across program executions?
A) Serialization
B) Garbage collection
C) Inheritance
D) Encapsulation
Answer: A)

75. When two objects of the same class have the same values but different references, they are:
A) Identical objects
B) Equivalent but distinct objects
C) Static objects
D) Transient objects
Answer: B)

76. Which of the following is true about a constant object in C++?
A) It can modify its member variables
B) It cannot call any function
C) It can call only constant member functions
D) It cannot be created using constructors
Answer: C)

77. What happens when an object is passed by value to a function?
A) The original object is modified
B) A copy of the object is created
C) A reference to the object is shared
D) The compiler throws an error
Answer: B)

78. When an object contains another object that can exist independently, the relationship is called:
A) Composition
B) Aggregation
C) Inheritance
D) Polymorphism
Answer: B)

79. Which of the following is responsible for cleaning up unused objects automatically in Java?
A) Destructor
B) Garbage Collector
C) Final method
D) System cleaner
Answer: B)

80. Which among the following can be considered a “message” to an object?
A) A method call
B) A data member
C) A constructor
D) A pointer
Answer: A)

81. In C++, if no constructor is defined, what happens when an object is created?
A) Compilation fails
B) Memory is not allocated
C) A default constructor is provided automatically
D) The program crashes
Answer: C)

82. Which of the following allows one object to copy the contents of another object?
A) Assignment operator
B) Copy constructor
C) Both A and B
D) Move constructor
Answer: C)

83. What is a dangling object reference?
A) A reference to an object that has been destroyed
B) A static reference
C) A null reference
D) A circular dependency
Answer: A)

84. What ensures that private data members of an object are not directly accessible from outside?
A) Inheritance
B) Encapsulation
C) Static binding
D) Dynamic dispatch
Answer: B)

85. When an object’s destructor is declared as virtual, it ensures:
A) Overloading
B) Proper destruction in inheritance hierarchy
C) Faster performance
D) Static dispatch
Answer: B)

86. Which among these statements is true about object serialization?
A) It hides data
B) It converts an object into a byte stream for storage or transmission
C) It copies an object in memory
D) It initializes class members
Answer: B)

87. What will happen if a destructor is private in a class?
A) Object creation fails
B) Objects cannot be destroyed outside the class
C) Copy constructor cannot be used
D) It disables all constructors
Answer: B)

88. Which of the following creates an object only once during program execution?
A) Local object
B) Static object
C) Singleton object
D) Global object
Answer: C)

89. Which feature allows an object to hide its implementation details from the outside world?
A) Polymorphism
B) Abstraction
C) Inheritance
D) Overloading
Answer: B)

90. When two or more objects work together to perform a task, it is called:
A) Encapsulation
B) Inheritance
C) Object collaboration
D) Static linkage
Answer: C)

91. Which of the following can be shared among all objects of a class?
A) Instance variables
B) Static methods and data
C) Constructors
D) Destructors
Answer: B)

92. The concept of “object persistence” refers to:
A) Object created in memory temporarily
B) Object that retains its state even after the program terminates
C) Object stored only in cache
D) Object reused in recursion
Answer: B)

93. Which of the following can be used to prevent creating multiple objects of a class?
A) Static variable
B) Constant data
C) Private constructor with a static instance
D) Friend function
Answer: C)

94. Which of these is an example of runtime object creation?
A) int x = 10;
B) Car c;
C) Car c = new Car();*
D) Car c();
Answer: C)

95. When an object is created on the heap, how is it typically destroyed?
A) Automatically
B) Using delete or garbage collector
C) When function ends
D) During compilation
Answer: B)

96. Which design pattern ensures only one instance of an object exists?
A) Factory pattern
B) Adapter pattern
C) Singleton pattern
D) Proxy pattern
Answer: C)

97. In Java, what is the superclass of all classes?
A) Base
B) Root
C) Object
D) Main
Answer: C)

98. Which function in Java is automatically invoked before an object is garbage collected?
A) dispose()
B) finalize()
C) destroy()
D) end()
Answer: B)

99. When two objects have the same behavior but belong to different classes, it demonstrates:
A) Polymorphism
B) Encapsulation
C) Aggregation
D) Composition
Answer: A)

100. In OOP, the term “object identity” refers to:
A) The uniqueness of each object even if its data is identical to another
B) The number of methods in the object
C) The inheritance chain of the object
D) The value of its attributes
Answer: A)