To simplify code in JSP expressions and scriptlets, we can use eight automatically defined variables, sometimes called implicit objects. They are request, response, out, session, application, config, pageContext, and page.

In the context of Core Java, “Predefined variables” or “implicit objects” typically refer to the objects that are automatically available to a Java program without the need for explicit declaration. These objects are part of the Java environment and provide information or functionality that can be used within a Java program.

Some commonly used predefined variables or implicit objects in Java include:

this: Refers to the current instance of the class.
super: Refers to the immediate parent class object.
args: The command-line arguments passed to the main method.
System.in: Represents the standard input stream.
System.out: Represents the standard output stream.
System.err: Represents the standard error output stream.
Runtime: Represents the Java runtime system.
Math: Provides mathematical operations.
String: Represents a sequence of characters and provides string-related operations.

It’s worth noting that the term “predefined variables” or “implicit objects” might be used in a more specific context, such as in JavaServer Pages (JSP), where objects like request, response, session, and application are considered implicit objects.

If you have a specific context or exam question in mind, please provide more details for a more accurate answer.