The primary use of Streams in Node.js is for handling data in a streaming fashion, especially for reading and writing data efficiently. They are commonly used for handling HTTP requests and responses, file I/O, and more, where data can be processed in smaller chunks without loading the entire dataset into memory.

In Express.js, you can handle errors occurring in asynchronous code within a route handler by calling next(error). This passes the error to the error-handling middleware or the default error handler, allowing you to centralize error handling. Using a try-catch block won't catch asynchronous errors, and the other options are not standard practices for error handling in Express.js.

Unit Testing focuses on verifying the functionality of individual components (or units) in isolation. It helps ensure that each component works correctly on its own.

If an error event is emitted in Node.js, but there is no listener attached to handle it, Node.js will throw an uncaught exception. This can lead to the termination of the Node.js process if the exception is not caught elsewhere in your code.

The buffer.write method in Node.js writes the string into the buffer as bytes and returns the number of bytes written. It's essential to understand that it deals with bytes, not characters, bits, or other units of data.

In a document-oriented NoSQL database, the "schema" defines the structure and data types of the documents within the database. Unlike traditional relational databases, NoSQL databases like MongoDB are schema-less, but they still rely on a flexible schema to define the structure of documents.

An appropriate use case for using a NoSQL database over a SQL database is real-time analytics on large datasets. NoSQL databases are often better suited for handling unstructured or semi-structured data at scale, making them a good fit for analytics. The other options are typically better handled by SQL databases.

OAuth 2.0 is a widely adopted authentication strategy for securing APIs accessed by various clients. It provides security features such as token-based authentication, authorization, and is suitable for both web clients and services. JWT is a token format and not an authentication strategy on its own. Basic Authentication and API Keys have limitations in terms of security and scalability.

In Express.js, the all() method is used to handle all HTTP methods (GET, POST, PUT, DELETE, etc.) for a specific route. It is equivalent in functionality to the any() method. The use() and match() methods do not provide the same functionality.

The Event Loop in Node.js handles asynchronous tasks by adding them to a queue and executing them in a non-blocking manner. It ensures that asynchronous tasks are processed in the background without pausing the main thread, allowing Node.js to remain responsive. The other options do not accurately describe how asynchronous tasks are handled by the Event Loop.