15 extra multiple-choice questions for Database Concepts (12th Standard Computer Science, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Which of the following is the best description of "Information" as defined in database concepts?
- A. It refers to raw facts stored in a computer that have no specific meaning on their own.
- B. It is processed, organized, and formatted data that can be utilized in a significant way.Correct
- C. It is a software-based tool used to write instructions to access and manipulate tables.
- D. It is the physical hard disk and storage media used to store database records.
Explanation. Data consists of raw, unprocessed facts, whereas information is processed data, organized and formatted to be utilized in a significant and meaningful way.
Q2
In a Relational Database Management System (RDBMS), what is the primary purpose of applying database normalization?
- A. To increase data redundancy by duplicating records across multiple physical drives.
- B. To divide data into multiple tables in such a way that unnecessary repetition is minimized.Correct
- C. To eliminate the need for using any query languages to fetch or retrieve records.
- D. To allow only a single user to access and write data at any given time.
Explanation. RDBMS uses normalization to divide data into tables to reduce data redundancy, which minimizes unnecessary repetition and helps maintain data consistency.
Q3
Which component of a Database Management System (DBMS) is responsible for interpreting the database access languages into executable database commands?
- A. Hardware
- B. SoftwareCorrect
- C. Data
- D. Procedures
Explanation. The DBMS software is the main program component that controls everything; it is capable of understanding the Database Access Languages and translating or interpreting them into database commands for execution.
Q4
In the Hierarchical database model developed by IBM, which of the following rules defines the relationship between parent and child nodes?
- A. A child can have many parents, and a parent can have only one child.
- B. A child can have only one parent, but a parent can have many children.Correct
- C. Both parents and children can have an unlimited number of parent-child relationships.
- D. Children nodes are completely independent and cannot be linked to any parent node.
Explanation. The hierarchical model represents a one-to-many relationship using a tree-like structure, where one child can have only one parent, but one parent can have many children.
Q5
How does the Network database model differ from the Hierarchical database model?
- A. In a network model, data is stored in flat files, whereas the hierarchical model uses tables.
- B. In a network model, a child record can have many parent nodes, representing many-to-many relationships.Correct
- C. The network model does not support any relationship mappings between its entities.
- D. The network model restricts each parent node to having at most one child node.
Explanation. Unlike the hierarchical model where a child record can have only one parent node, the network model allows a child to have many parent nodes, representing many-to-many relationships.
Q6
In an Entity-Relationship (ER) diagram, what geometric shape is used to represent attributes?
- A. Rectangle
- B. Diamond
- C. EllipseCorrect
- D. Triangle
Explanation. In ER model diagrams, rectangles represent entities, ellipses represent attributes (which describe the characteristics of an entity), and diamonds represent relationships.
Q7
In the Object database model, how are specialized objects like "Circle" or "Rectangle" related to a general object like "Shape"?
- A. They are completely independent and cannot share any properties.
- B. They inherit attributes and behaviors from the "Shape" object.Correct
- C. They are stored as flat text strings inside the "Shape" object.
- D. They act as parent nodes that control the "Shape" object in a tree hierarchy.
Explanation. The object model represents real-world objects, attributes, and behaviors, allowing objects like Circle, Rectangle, and Triangle to inherit from a base object like Shape.
Q8
Which type of database user is primarily responsible for managing security, licenses, user accounts, and access permissions in a DBMS?
- A. Application Programmer
- B. Database Administrator (DBA)Correct
- C. End User
- D. Database Designer
Explanation. The Database Administrator (DBA) manages the complete DBMS, taking care of security, license keys, and managing user accounts and access privileges.
Q9
If table A is linked to table B in a One-to-Many relationship, which of the following statements is true regarding their rows?
- A. One row in table A can link to many rows in table B, and one row in table B can link to many rows in table A.
- B. One row in table A is linked to many rows in table B, but one row in table B is linked to only one row in table A.Correct
- C. Every single row in table A must be identical to every corresponding row in table B.
- D. Rows in table A are completely prevented from linking to any rows in table B.
Explanation. In a One-to-Many relationship, one row in table A is linked to many rows in table B, but one row in table B is linked to only one row in table A.
Q10
In Relational Algebra, what is the behavior of the PROJECT (\(_\Pi\)) operation on its output relation?
- A. It selects a subset of rows from the table that satisfy a specific horizontal condition.
- B. It eliminates all attributes of the input relation except those specified in the projection list.Correct
- C. It joins all rows of two distinct tables and keeps all duplicate records.
- D. It changes the data types of all selected columns to floating-point numbers.
Explanation. The projection (\(_\Pi\)) operation defines a vertical subset of a relation. It eliminates all attributes of the input relation except those mentioned in the projection list and automatically removes duplicate rows.
Q11
When using the SELECT (\(_\sigma\)) operation in Relational Algebra, what does the subscript 'c' in \(_\sigma_c(R)\) represent?
- A. The column index where the search begins.
- B. The selection condition applicable to the attributes of relation R.Correct
- C. The count of duplicate tuples to be removed from the relation.
- D. The name of the database file that holds relation R.
Explanation. The general form of a SELECT operation is \(_\sigma_c(R)\), where R is the relation (table) and 'c' is the selection condition on the attributes of R.
Q12
In Relational Algebra, which set-theory operation requires that the two participating relations be union-compatible?
- A. Cartesian Product
- B. IntersectionCorrect
- C. Projection
- D. Selection
Explanation. For the INTERSECTION (\(_\cap\)) operation (and also UNION), the participating relations A and B must be union-compatible.
Q13
If relation A contains 4 tuples and relation B contains 3 tuples, how many tuples will be present in the resulting Cartesian Product (\(A \times B\))?
- A. 7 tuples
- B. 1 tuple
- C. 12 tuplesCorrect
- D. 64 tuples
Explanation. The Cartesian Product combines two relations. The size of the resulting relation is the product of the number of tuples in both relations (4 times 3 is 12).
Q14
What is the result of the Set Difference (\(A - B\)) operation in Relational Algebra?
- A. A relation containing all tuples that are present in both A and B.
- B. A relation containing all tuples that are in A but not in B.Correct
- C. A relation containing all tuples that are in B but not in A.
- D. A relation combining all attributes of A and B without any row filtering.
Explanation. The result of A - B is a relation that includes all tuples that are in relation A but are not present in relation B.
Q15
Which relational algebra operation is classified as a Unary Relational Operation?
- A. Union (\(_\cup\))
- B. Cartesian Product (\(X\))
- C. Select (\(_\sigma\))Correct
- D. Intersection (\(_\cap\))
Explanation. Relational algebra operations are divided into Unary Relational Operations (such as SELECT and PROJECT, which operate on a single table) and Set Theory Operations (such as UNION, INTERSECTION, DIFFERENCE, and CARTESIAN PRODUCT).
