HashedIn by Deloitte interview question

1) What is Encapsulation and Polymorphism 2) Difference between Abstraction and Interface 3) Difference between IQueryable and IEnumerable 4) Explain Extension Methods, Anonymous method, Middleware 5) Write a C# program for reversing of the Whole String. 6) Write a C# program to print index of Array from given Array Of Numbers [2, 7, 11, 15] whose Sum is 9.