CUET UG 2025 Computer Science Previous Year Solved Paper

wer: 3. Cartesian Product
• The Cartesian Product combines every tuple of the first relation with
every tuple of the second relation.
• Example:
• Course = {C1, C2}, Student = {S1, S2, S3}
• Course × Student = {(C1,S1), (C1,S2), (C1,S3), (C2,S1), (C2,S2), (C2,S3)}
• Other operations like Union, Intersection, or Set Difference do not
combine all tuples in this way.
Tip: Whenever you see × in relational algebra, think “every combination” →
Cartesian Product.

wer: Option 4
Name
Hobbies
Anu
Dance
Anuj
Music
Pranav
Reading
Anuj
Reading

wer: 3. Foreign key
The Foreign Key is used to represent the relationship between two relations
(tables).
Here, the Deptno field in the Employee table refers to the Deptno field in the
Department table — linking employees to their departments.

wer: 3. Default

A default value is automatically assigned to a column when no value is
provided during data insertion.

wer: 1. ALTER TABLE StudAtt ADD PRIMARY KEY(Rno, Attdate);
To add a composite primary key (using more than one column) after table
creation, the correct SQL syntax is:

wer: 1. returns records without repetition
The DISTINCT keyword in a SELECT statement is used to eliminate duplicate
rows from the result set, ensuring that only unique records are returned.

wer: 3. LIKE operator
The LIKE operator is used in SQL to search for a specific pattern in a column,
often with wildcards like:
• % → matches any sequence of characters
• _ → matches a single character

wer: 1. 3
The MONTH("2010-03-05") function returns the numeric value of the month
from the given date.
Here, the date is 2010-03-05, so the month is March, which corresponds to 3.

wer: 1. (A) - (III), (B) - (I), (C) - (II), (D) - (IV)
Function
Description

count(marks)
Counts all non-null values in the
marks column → (III)
count(*)
Counts all rows (including those with
NULLs) → (I)
avg(marks)
Finds average of non-null marks →
(II)
sum(marks)
Finds sum of all marks → (IV)

wer: 1. 30
The AVG() function ignores NULL values when calculating the average.
Given Data:
Marks = 20, 40, NULL, 30
Calculation:
Average = (20 + 40 + 30) / 3 = 90 / 3 = 30

wer: 2. Intersect
• The INTERSECT operation in relational algebra returns only the tuples
that are common to both relations.
• Union returns all tuples from both relations, Set Difference returns
tuples in one relation but not in the other, and Cartesian Product pairs all
tuples from the first relation with all tuples from the second.

wer: 3. 192.168.0.178.
Reason: A valid IPv4 address has four numbers (0–255) separated by dots.
Option 1 is a MAC address, option 2 has 256 (invalid), option 4 has -1
(invalid), so only option 3 is correct.

wer: 2. (C), (A), (D), (B)

Explanation: In Python:
• try: block comes first to execute code that may raise an exception.
• except: block handles specific exceptions if they occur.
• else: block executes if no exception occurs.
• finally: block executes always, whether an exception occurred or not.
So the sequence is: try → except → else → finally.

wer: 3. Pickling.
• Pickling is the process of converting a Python object in memory into a
byte stream so it can be saved to a file or sent over a network.
• De-serialization (or unpickling) is the reverse process—converting byte
streams back into Python objects.
• read() and write() are file operations, not object-to-byte conversion
processes.

wer: 3.
• To read data from a binary file using pickle, the file must be opened in
binary read mode ("rb").
• The pickle.load() function is used to load the object from the file.
• Other options are incorrect because:
• Option 1: Opens in text mode "r", not binary.
• Option 2: Uses f1.load() instead of pickle.load(f1) and has a typo
(f1.closen).
• Option 4: Uses f1.read(), which reads raw bytes but doesn’t deserialize
the object.

wer: 2. file.open("data.txt","r+").

• "r+" mode opens a file for both reading and writing.
• "rw" and "rw+" are invalid modes in Python.
• file.open("data.txt") opens the file in read-only mode by default.

wer: 1. Polish expression.
• In a Polish expression (prefix notation), the operator comes before its
operands.
o Example: + 5 3 means 5 + 3.
• Infix expression: Operator is between operands (5 + 3).
• Postfix expression: Operator is after operands (5 3 +).
• Reverse Polish expression is another name for postfix notation, not
prefix.

wer: 3. 31
1. Postfix evaluation: Operands are pushed to a stack; operators act on the
most recent operands.
Expression: 24 5 7 * 5 / +
• Step 1: Push 24 → Stack: [24]
• Step 2: Push 5 → Stack: [24, 5]
• Step 3: Push 7 → Stack: [24, 5, 7]
• Step 4: * → Pop 7 and 5, multiply: 5 * 7 = 35 → Push 35 → Stack: [24, 35]
• Step 5: Push 5 → Stack: [24, 35, 5]
• Step 6: / → Pop 5 and 35, divide: 35 / 5 = 7 → Push 7 → Stack: [24, 7]
• Step 7: + → Pop 7 and 24, add: 24 + 7 = 31 → Push 31 → Stack: [31]

wer: 4. LIFO, one.
• A STACK follows the LIFO (Last In, First Out) principle.
• Insertion (push) and deletion (pop) happen from one end only, called
the top of the stack.
• FIFO (First In, First Out) applies to queues, not stacks.

wer : 2. Queue.
• A queue follows the FIFO (First In, First Out) principle, which is ideal for
handling requests in the order they arrive.
• In the given scenario, users’ requests to view results should be served in
the order they arrive, especially when the server has a limit on
concurrent requests.
• Stack (LIFO) would serve the most recent request first, which is not fair.
• List and Dictionary don’t inherently manage order or concurrency like a
queue does.

wer: 2. (A), (B) and (C) only.
• isEmpty (A): Checks if the queue is empty before performing dequeue to
avoid underflow.
• isFull (C): Checks if the queue is full before performing enqueue to avoid
overflow.
• peek (B): Allows viewing the front element without removing it, which
is often needed in efficient queue operations.
• update (D): Not a standard operation for basic queue functionality.

wer: 3. Between A to D.
• In networking, repeaters are used when the signal distance exceeds the
maximum allowable range for proper transmission.

• From the distance table:
o A to B = 20 m (within limit)
o A to C = 50 m (within limit)
o A to D = 110 m (exceeds typical Ethernet limit of 100 m) →
repeater needed
o A to E = 0 m (no distance, no repeater needed)
So, a repeater is required between A and D to ensure signal integrity.

wer: 3) 24 bits
A MAC (Media Access Control) address is a 48-bit unique identifier for a
network device. It is divided into two parts: the OUI and the device-specific ID.
The OUI identifies the manufacturer of the device and occupies the first 24 bits
(or first 3 bytes) of the MAC address. The remaining 24 bits are used by the
manufacturer to assign unique IDs to each device.

wer: 3) (B), (A), (D), (C)
In binary search, you first initialize the pointers with first = 0 and last = n-1
(B). Then, calculate the middle index mid = (first + last)//2 (A). Compare
numList[mid] with the key: if equal, print the position; if numList[mid] > key,
update last = mid-1; otherwise, update first = mid+1 (D). If the key is not
found after the search, print "Search unsuccessful" (C).

wer: 2) gets reduced by half
Binary search works by repeatedly dividing the search area in half. You
compare the key with the middle element: if the key is smaller, you discard the
right half; if larger, you discard the left half. This reduces the search area by
half each time, making the search very efficient.

wer: 2) The key is in the second half
In an ascending sorted list, all elements after the middle element are greater
than the middle element. If the middle element is less than the key, the key
cannot be in the first half (which contains smaller elements). Therefore, the
key must be in the second half of the list.

wer: 2. (A), (C), (D), (B)
• Bubble sort works by repeatedly swapping adjacent elements if they are
in the wrong order.
• After each pass, the largest element “bubbles up” to its correct position.
• Applying this to the given list gives the sequence:
1. (A) – during first pass (partial swaps start)
2. (C) – after first pass
3. (D) – after second pass
4. (B) – final sorted list
Q.28
Answer: 3. Time complexity
• Time Complexity is a theoretical measure that tells us how much time an
algorithm takes to run depending on the size of the input data.
• It helps us compare different algorithms without actually running them
— by analyzing how their runtime increases as input grows.

Answer: 3. Time complexity
Time complexity measures how the running time of an algorithm grows as the input size increases. That makes option 3 the correct term for the amount of time an algorithm takes to process data.

wer: (2) Mean is the average of numeric values of an attribute.
The mean represents a measure of central tendency, not a measure of
variability. Measures of variability (or dispersion) describe how spread out

the data is, such as range, variance, or standard deviation. Hence, the
statement about the mean is incorrect.

wer: (3) Unstructured data
When recording a video, the data generated does not follow a fixed format or
organized structure (like rows and columns). It consists of raw media files —
visuals, audio, and frames — which cannot be easily stored in traditional
databases. Such data is known as unstructured data.

wer: 1. 50
The mode is the value that occurs most frequently in a given dataset.
The highest frequency = 5, which corresponds to 50 kg.

wer: 2. (A) → (III), (B) → (I), (C) → (II), (D) → (IV)
List-I
Explanation
List-II
(Match)
(A) Primary Key
A field (attribute) that uniquely
identifies each record (tuple) in a
table.
(III)
(B) Degree
The total number of attributes
(columns) in a table.
(I)
(C) Foreign Key
An attribute used to relate two
tables (establishes referential
integrity).
(II)
(D) Constraint (spelled as
“Copotroint” in question)
A restriction or rule applied on
the type of data inserted in a
column.
(IV)

wer: 3. Domain
In SQL, each column (attribute) in a table can take values from a specific set of
permissible values, known as its domain.
For example, if a column “Age” can only have integer values between 0 and
120, then that range defines the domain of the column.

wer: 1. Data Dictionary
Meta-data means “data about data” — it describes the structure, organization,
and properties of data stored in a database.
A Data Dictionary stores this kind of information — such as table names,
column names, data types, constraints, etc. Hence, it acts as a catalog of
metadata.

wer: 4. Scalar
Single row functions operate on one row at a time and return one result per
row.
These are also called scalar functions, because they return a single (scalar)
value for each row of input.

wer: 1. DROP TABLE SPORTS;
In SQL:
• The DELETE command removes rows (data) from a table but keeps the
table structure.
• The DROP TABLE command removes the entire table permanently,
including its structure and data.

Hence, to delete the table ‘sports’ permanently, the correct command is:
DROP TABLE SPORTS;

wer: 3. (A), (B), (C) and (D)
In SQL, the following are text (string) functions:
• MID() → Extracts a substring from text (sometimes written as
SUBSTRING() or MID()).
• INSTR() → Returns the position of a substring within a string.
• SUBSTR() → Extracts a part of a string (similar to MID).
• LENGTH() → Returns the number of characters in a string.
So, all four — MID, INSTR, SUBSTR, LENGTH — are text functions.

wer: (A) → (II), (B) → (IV), (C) → (I), (D) → (III)
Let’s correctly match the networking terms:
List-I
Explanation
List-II
(Match)
(A) Router
A network device used to connect different
networks.
(II)
(B) Ethernet Card
Also known as a Network Interface Card
(NIC) — helps connect a computer to a
network.
(IV)
(C) Ring
Refers to a network topology where each
device is connected in a circular manner.
(I)
(D) PAN (Personal
Area Network)
A type of network used for short-range
communication (like Bluetooth).
(III)

wer: 3. HTML
HTML (HyperText Markup Language) is the standard language used to create
and design web pages.
It defines the structure of a webpage using elements like headings,
paragraphs, links, images, and tables.

wer: 4. (A) → (II), (B) → (I), (C) → (IV), (D) → (III)
List-I
Explanation
List-II
(Match)
(A) Modem
A Modulator–Demodulator that converts
digital signals to analog and vice versa for
internet communication.
(II)
(B) RJ45
An 8-pin connector used with Ethernet
cables in networking.
(I)
(C) Network
Interface Unit
Refers to an Ethernet card that connects a
computer to a network.
(IV)
(D) ISP (Internet
Service Provider)
An organization providing internet access
services.
(III)

wer: 1. The range of frequencies available for transmission of data through
that channel.
Bandwidth refers to the range of frequencies that a communication channel
can use for data transmission.

A higher bandwidth means more data can be transmitted per second — just
like a wider road allows more vehicles to pass.

wer: 2. (A) and (C) only (because 1 Gbps = 1024 Mbps).1 Gbps stands for
1 Gbps (Gigabit per second) means 1 billion bits per second.
In networking terms:
1 Gbps=1024 Mbps1 \text{ Gbps} = 1024 \text{ Mbps}1 Gbps=1024 Mbps
Other options like Kbps, bps (230 bps or 22 bps) are much smaller and
incorrect.

wer: 3. Twisted Pair Cable
The description — “less expensive, commonly used in telephone lines and
LANs, available in two types: Unshielded and Shielded” — clearly refers to
Twisted Pair Cable.
• Unshielded Twisted Pair (UTP): Used in telephone lines and LAN
connections.
• Shielded Twisted Pair (STP): Used where extra protection from
interference is needed.

wer: 2. A cookie is edited only by the website that created it, the client’s
computer acts as a host to store the cookie.
A cookie is a small file or data packet that a website stores on the user’s
(client’s) computer, not on the server.
It helps websites remember user information such as login details,
preferences, or items in a shopping cart.
Only the website that created the cookie can read or modify it.

wer: 3. Denial of Service
The scenario describes a situation where an attacker overloads a server or
network with fake or illegitimate requests, making it unavailable to legitimate
users.
This is known as a Denial of Service (DoS) attack.

wer: 4. SSL Digital Certificate
Websites that use HTTPS (HyperText Transfer Protocol Secure) ensure secure
data transfer between the browser and the server.
To establish this secure connection, they require an SSL (Secure Sockets Layer)
Digital Certificate, which encrypts the data and verifies the website’s
authenticity.

wer: 4. ERROR
Let’s analyze the query:
SELECT LENGTH(MID('INFORMATICS PRACTICES',5,-5));
• The function MID('INFORMATICS PRACTICES', 5, -5) tries to extract a
substring starting from position 5 with a negative length (-5).
• In SQL, the MID() (or SUBSTRING()) function does not accept negative
length values.
• Using a negative number for length produces an invalid argument error.
Hence, the query will not execute successfully.

wer: 1. (A) → (III), (B) → (IV), (C) → (II), (D) → (I)
Let’s match each SQL term with its correct category

List-I
Explanation
List-II
(Match)
(A) GROUP
BY
Used to group rows based on a column for
performing aggregate functions (works with
HAVING clause).
(III)
(B) MID()
A text function that extracts a substring from a
string.
(IV)
(C)
COUNT()
An aggregate function that counts the number of
rows or values.
(II)
(D) MOD() A mathematical function that returns the
remainder of a division.
(I)

wer: 2. YYYY-MM-DD HH:MM:SS
In SQL, the NOW() function returns the current date and time in the standard
datetime format:
YYYY-MM-DD HH:MM:SS\text{YYYY-MM-DD HH:MM:SS}YYYY-MM-
DD HH:MM:SS
Example:
2025-10-14 09:30:45

wer: 1. 9900
The SQL function ROUND(number, n) rounds a number to n digits.
• If n is positive, it rounds to that many decimal places.
• If n is negative, it rounds to the nearest 10, 100, 1000, etc.
Here:

ROUND(9873.567, -2)
• The -2 means round to the nearest hundred.
• 9873.567 → the hundreds digit is 8 and the tens digit is 7 (≥ 5), so it
rounds up to 9900.