Serialization is the process of converting an object into a stream of bytes in order to store the object or transmit it to memory, a database, or a file. Its main purpose is to save the state of an object in order to be able to recreate it when needed. The reverse process is called deserialization.

 The System.Security.Cryptography namespace provides cryptographic services, including secure encoding and decoding of data, as well as many other operations, such as hashing, random number generation, and message authentication.

  There are five types of thread priority levels.Default priority level is 2: 

1. 0 - Zero level
2. 1 - Below Normal
3. 2 - Normal

 Here I have assumed that table name is Cars and Carid is primary key.

DELETE FROM CARS WHERE carId NOT IN (select MAX(carId)AS carId from Cars group by Model)

 WCF endpoint provides information to the clients about the service to communicate with.It has three basic elements i.e. Address, Binding and Contract.

Properties areused to read, write and compute the values of private fields.Properties can be used as though they are public data members, but they are actually special methods called accessors. This enables data 

Yes, foreign key can have multiple NULL values.

Yes, unique key can accept only one NULL value.

No, Primary keys cannot be null.

 Yes foreign key can reference non-primary key if it is a unique key.