24 OOP questions from the C# bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship
B.a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
C.a class marked so that no other type may derive from it, preventing further extension of the hierarchy
D.the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
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2. Which term means: "the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship"?
Junior
A.Property
B.Sealed class
C.Inheritance
D.Abstract class
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3. Which statement is correct?
Junior
A.Inheritance — the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship
B.Inheritance — a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
C.Inheritance — a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
D.Inheritance — a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
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4. What is Interface?
Junior
A.a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time
B.a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
C.a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
D.redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
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5. Which term means: "a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them"?
Junior
A.Abstract class
B.Override
C.Inheritance
D.Interface
Answer + AI explanation with Pro
6. Which statement is correct?
Junior
A.Interface — the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship
B.Interface — redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
C.Interface — a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
D.Interface — the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
Answer + AI explanation with Pro
7. What is Abstract class?
Mid
A.redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
B.a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
C.a class marked so that no other type may derive from it, preventing further extension of the hierarchy
D.a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
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8. Which term means: "a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete"?
Mid
A.Abstract class
B.Interface
C.Override
D.Method hiding
Answer + AI explanation with Pro
9. Which statement is correct?
Mid
A.Abstract class — the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
B.Abstract class — redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
C.Abstract class — a class marked so that no other type may derive from it, preventing further extension of the hierarchy
D.Abstract class — a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
Answer + AI explanation with Pro
10. What is Sealed class?
Mid
A.a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
B.a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
C.a class marked so that no other type may derive from it, preventing further extension of the hierarchy
D.the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
Answer + AI explanation with Pro
11. Which term means: "a class marked so that no other type may derive from it, preventing further extension of the hierarchy"?
Mid
A.Sealed class
B.Method hiding
C.Override
D.Virtual method
Answer + AI explanation with Pro
12. Which statement is correct?
Mid
A.Sealed class — a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time
B.Sealed class — a class marked so that no other type may derive from it, preventing further extension of the hierarchy
C.Sealed class — the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
D.Sealed class — the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship
Answer + AI explanation with Pro
13. What is Virtual method?
Mid
A.a class marked so that no other type may derive from it, preventing further extension of the hierarchy
B.a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time
C.a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
D.the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
Answer + AI explanation with Pro
14. Which term means: "a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time"?
Mid
A.Property
B.Virtual method
C.Override
D.Interface
Answer + AI explanation with Pro
15. Which statement is correct?
Mid
A.Virtual method — a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
B.Virtual method — a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time
C.Virtual method — a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
D.Virtual method — redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
Answer + AI explanation with Pro
16. What is Override?
Mid
A.a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time
B.the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
C.a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
D.a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
Answer + AI explanation with Pro
17. Which term means: "the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference"?
Mid
A.Method hiding
B.Override
C.Property
D.Virtual method
Answer + AI explanation with Pro
18. Which statement is correct?
Mid
A.Override — a base-class method explicitly marked to permit a derived class to supply a replacement implementation that is selected at run time
B.Override — the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
C.Override — the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship
D.Override — a class marked so that no other type may derive from it, preventing further extension of the hierarchy
Answer + AI explanation with Pro
19. What is Method hiding?
Senior
A.a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
B.redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
C.a class marked so that no other type may derive from it, preventing further extension of the hierarchy
D.the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
Answer + AI explanation with Pro
20. Which term means: "redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type"?
Senior
A.Override
B.Abstract class
C.Method hiding
D.Inheritance
Answer + AI explanation with Pro
21. Which statement is correct?
Senior
A.Method hiding — a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
B.Method hiding — a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
C.Method hiding — redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
D.Method hiding — a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
Answer + AI explanation with Pro
22. What is Property?
Junior
A.a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
B.the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
C.redeclaring an inherited member with the new modifier so the derived version shadows rather than polymorphically replaces the base version, dispatch depending on the static reference type
D.the mechanism by which a derived type acquires the members of a base type, enabling reuse and an is-a relationship
Answer + AI explanation with Pro
23. Which term means: "a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods"?
Junior
A.Property
B.Interface
C.Method hiding
D.Abstract class
Answer + AI explanation with Pro
24. Which statement is correct?
Junior
A.Property — a reference type defining a contract of members with no instance state, which a class or struct can implement, and a type may implement many of them
B.Property — the keyword applied in a derived class to replace a base member's implementation while preserving polymorphic dispatch through a base reference
C.Property — a class that cannot be instantiated directly and may declare members without implementation that derived classes must complete
D.Property — a member that exposes a getter and/or setter accessor to read or write a value, syntactically used like a field but backed by methods
Answer + AI explanation with Pro
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