In the http module, the close event of the server object is emitted when the server closes. This event allows you to perform cleanup or take action when the server is shutting down. The other options (end, disconnect, terminate) do not represent the server closing event in the HTTP module.

The for...of statement in JavaScript creates a loop that iterates over array-like objects, which include arrays, strings, maps, sets, and other objects that have iterable properties. It's particularly useful for iterating over the values of such objects.

In Node.js, the Event Loop operates on a single Core, not a thread or process. This single-threaded event loop design is one of the key features of Node.js, making it suitable for I/O-bound tasks as it can efficiently handle asynchronous operations without the overhead of multiple threads or processes.

The concept of defining a blueprint for the data in the database is known as "Schema." A schema defines the structure, relationships, constraints, and integrity rules of the data stored in a database.

In Node.js, when an EventEmitter instance experiences an error, the typical event that is emitted is 'error'. This event allows you to handle errors that occur within event listeners attached to the EventEmitter.

In Node.js, you can create a buffer instance using the Buffer.alloc(size) method, where size is the desired size of the buffer in bytes. The new Buffer() constructor is deprecated, and the other options are not valid ways to create a buffer in Node.js.

Full-text search is most appropriately used when searching for specific keywords within a large body of text, such as searching for documents or articles containing certain words or phrases. It allows for complex text-based queries, making it ideal for content-heavy applications.

In JavaScript, you can use the unshift method to add an item to the beginning of an array. The push method adds an item to the end of an array. append and insert are not native array methods in JavaScript.

The primary purpose of using an Object-Relational Mapper (ORM) like Sequelize is to facilitate database interactions by mapping JavaScript objects to database tables. It abstracts the underlying database, making it easier to work with databases and reducing the need for writing raw SQL queries. The other options are not the primary purposes of an ORM.

The Update operation in CRUD (Create, Read, Update, Delete) operations is used to modify existing data in the system. It allows you to make changes to existing records.