Explanation

math.h is the standard C/C++ header file that contains declarations for common mathematical functions like sqrt(), pow(), sin(), etc.

It must be included when using built-in math operations in programs.

Explanation

The else keyword is used to provide an alternative block of code if the if condition is false.

It works with if to handle two different choices in decision-making.

Explanation

Address consists of text (street, city, etc.).

It is non-numerical.

Marks, bank balance, and roll number are numerical values.

Explanation

A command-line interface is used by DOS systems.

By typing a program's filename at the command prompt, a program can be launched.

Explanation

A foreign key is used to link two tables and can contain duplicate values.

In contrast, primary, candidate, and even secondary keys are typically unique.

Explanation

A primary key must be unique for each record and never change.

Zip code is not unique (many people can share the same zip code), so it's not suitable as a primary key.

Explanation

Explanation

Explanation

In an Entity-Relationship (E-R) diagram, a rectangle represents an Entity.

Attributes are shown as ellipses.

Relationships are shown as diamonds.

Explanation

An attribute describes the characteristics or properties of an object or entity (e.g., name, age, color).

It helps define what the object is like.