HashSet is an unordered collection.
The default EqualityComparer checks whether the element supplied to the HashSet is unique or not.
HashSet provides functionality for "conceptual sets" where the rules for membership can be specified without actually creating all of the items.
All of the above
A calendar divides time into units, such as weeks, months, and years. The number, length, and start of the divisions vary in each calendar. Useful resources, Calendar class
A Nullable type is a reference type.
An implicit conversion exists from any non-nullable value type to a nullable form of that type.
A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T
Useful resources, Nullable Types
You can request that the garbage collector processes a generation if it determines that it is appropriate at specific points in your code
You can control the intrusiveness of the garbage collector (how often it performs collections) while your program is running
You can control the intrusiveness of the garbage collector (how often it performs collections) only during application initialization
You should specify LowLatency when using Concurrent Server Garbage Collection to improve memory utilization
The compiler generates a backing field that is completely inaccessible from the application code.
The compiler generates a backing field that is accessible via reflection.
The compiler generates a code that will store the information separately from the instance to ensure its security.
In general, you can’t access. But there might be different stories. According to the accepted answer of Is it possible to access backing fields behind auto-implemented properties, you can do it, but is not confirmed nor provided any reference. So, as of now, our answer is The compiler generates a backing field that is completely inaccessible from the application code. Useful resources,Auto-Implemented Properties
You declare (explicitly or implicitly) the accessibility of the property and get and set assessors, but do not provide any implementation or backing field
You attribute a member field so that the compiler will generate get and set assessors
The compiler creates properties for your class based on class level attributes
They are properties which are automatically invoked as part of the object construction process
Useful resources, Auto-Implemented Properties
All of the above
Useful resources, ASP.NET State Management
Reads and writes of the following data types are atomic: bool, char, byte, sbyte, short, ushort, uint, int, float, and reference types. In addition, reads and writes of enum types with an underlying type in the previous list are also atomic. Reads and writes of other types, including long, ulong, double, and decimal, as well as user-defined types, are not guaranteed to be atomic. Useful resources, Atomicity of variable references
It is pure Object Relational (O/R) model.
It is a set of enhancements to the DataSet and DataTable classes.
It requires the use of SQLServer as the database.
Because LINQ is based on Queries, it cannot be used to modify the data in the database
They must handle case-sensitivity identically in both the GetHashCode() and Equals() methods.
Key objects must be immutable for the duration they are used within a HashTable.
Get HashCode() must be overridden to provide the same result, given the same parameters, regardless of reference equality unless the HashTable constructor is provided with an IEqualityComparer parameter.
Each Element in a HashTable is stored as a Key/Value pair of the type System.Collections.DictionaryElement
All of the above
Useful resources, Hashtable