PARTech interview question

1.) OOPS Concepts 2.) Polymorphism -Overriding and Method Hiding 3.) Asked to write Linq Queries 4.) Dependency Injection 5.) SOLID 6.) Constructors, Static Constructors 7.) Write a Program in c# 8.) Asked to find an integer occurring only once in array containing all integers twice. 9.) Abstract Class (Can be instantiated or not) and Interface 10.) REST APIs - > HTTP Request Types i.e. POST, PUT, GET, DELETE, PATCH 11.) Azure Services i have used like Privilege Identity Management 12.) Middlewares in .NET 13.) Cosmos DB 14.) Deep functionality of functions like how to submit the form, Write complete Syntax