In SQL, what does the command ALTER TABLE r ADD A D; do?
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Correct answer: (A) Adds a new attribute A of data type D to table r.
BEL PE · Topic-wise previous year questions
Computer Science Previous Year Questions (page 2)
200 Computer Science questions asked in BEL PE previous year papers, each with the correct answer and explanation. Read them free on UTpaper, or attempt the full papers as timed online tests.
- 200 questions
- 7 topics
- Official answer key
- Free
Practise by topic
Which of the following shows the correct order of the four main activities in the Requirements Engineering process?
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Correct answer: (C) Feasibility study → Requirements elicitation and analysis → Requirements specification → Requirements validation
Consider the array [5, 1, 4, 2, 8]. After the first pass of Bubble Sort to sort array elements in ascending order, what is the state of the array?
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Correct answer: (B) [1, 4, 2, 5, 8]
Which statement correctly reads a string from a text file into a character array str?
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Correct answer: (D) fgets(str, sizeof(str), fp);
Which of the following is a use of Compiler technology in embedded systems?
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Correct answer: (A) Generate efficient machine code for hardware constraints
If SetConsoleMode() is called with an input handle (STD_INPUT_HANDLE), which of the following mode flags CANNOT be used?
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Correct answer: (B) ENABLE_WRAP_AT_EOL_OUTPUT
In an FCFS-scheduled system, five processes arrive at time 0:
P1 (CPU-bound, 20 ms) and P2–P5 (I/O-bound, 2–5 ms).
Which outcome is most likely under FCFS?
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Correct answer: (D) I/O-bound processes face starvation due to the convoy effect caused by P1.
Consider the following binary tree:
A is the root. A has left child B and right child C. B has left child D and right child E. C has a right child F.
If an in-order traversal is performed on this tree, what will be the correct order of visiting nodes?
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Correct answer: (A) D B E A C F
When borrow = 1 in binary subtraction, what happens to the next higher bit position?
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Correct answer: (B) It decreases by 1.
A Mealy Machine outputs '1' when the current input bit is different from the previous input bit, otherwise it outputs '0'. Assume the previous input is 0 before the first symbol. What is the output sequence for the input string 'x = 10011'?
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Correct answer: (C) 11010
The equivalent hexadecimal representation for the binary number 1011101.1101 is ______.
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Correct answer: (B) 5D.D
If an NFA has 4 states, what is the maximum number of states possible in the equivalent DFA?
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Correct answer: (C) 16
A computer system has a 16-bit address bus and uses byte-addressable memory. The main memory consists of two memory chips, each of size 32 KB. If the address space begins at 0000H, which of the following represents the correct address range for the second memory chip?
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Correct answer: (D) 8000H – FFFFH
Which of the following criteria does the KNN algorithm use to make decisions?
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Correct answer: (C) Majority vote among nearest neighbors
Which statement about assertions in a relational database is true regarding data validity?
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Correct answer: (C) They maintain data validity through complex or cross-table rules.
In the Post Office Protocol (POP3), which of the following statements is true regarding message storage and retrieval?
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Correct answer: (C) Once downloaded, messages are typically deleted from the server.
In non-preemptive scheduling, when does context switching occur?
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Correct answer: (B) Only when the process finishes
Which data structure is most useful for implementing the symbol table during lexical analysis?
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Correct answer: (B) Hash Table
In a banking system, a transaction T1 transfers ₹300 from Account A to Account B. Balances are stored in a table Accounts(AccNo, Balance) with the constraint:
CHECK (Balance >= 0)
Suppose the following sequence occurs:
1. T1 deducts ₹300 from Account A.
2. System crashes before adding ₹300 to Account B.
3. The system restarts without recovery.
Which component of ACID has been compromised to the greatest extent in this case?
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Correct answer: (B) Atomicity
A data scientist is developing a predictive model for loan default detection using a dataset that contains labelled examples of previous loan applications marked as 'defaulted' or 'not defaulted'. However, during model training, the algorithm shows very high accuracy on training data but performs poorly on new unseen test data. Despite adding more labelled data, the issue persists. Which of the following best explains the underlying problem in the supervised learning process?
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Correct answer: (A) The model suffers from overfitting due to poor generalisation.
Consider the following Java code:
class Parent {
int x = 10;
void show() { System.out.println("Parent: " + x); }
}
class Child extends Parent {
int x = 20;
void show() { System.out.println("Child: " + x); }
}
public class Test {
public static void main(String[] args) {
Parent obj = new Child();
System.out.println(obj.x);
obj.show();
}
}
What will be the output of this program?
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Correct answer: (D) 10 Child: 20
Which of the following algorithms correctly traverses all elements of a one-dimensional array A from index lower_bound to upper_bound?
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Correct answer: (B) Step 1: SET I = lower_bound Step 2: Repeat Steps 3 to 4 while I <= upper_bound Step 3: Apply process to A[I] Step 4: SET I = I + 1 Step 5: EXIT
Analyse the following C program and predict its output.
#include <stdio.h>
int main() {
FILE *fp;
if ((fp = fopen("temp.txt", "r")) == NULL)
printf("Error");
else
fclose(fp);
fclose(fp);
return 0;
}
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Correct answer: (D) Undefined behavior
During an SMTP session, a client communicates with a mail server to send an email.
Consider the following sequence of SMTP commands and responses observed in a network trace:
S: 220 mail.example.com ESMTP Postfix
C: HELO client.host.com
S: 250 mail.example.com Hello client.host.com
C: MAIL FROM:<alice@example.com>
S: 250 OK
C: RCPT TO:<bob@example.net>
S: 550 No such user here
C: RCPT TO:<carol@example.net>
S: 250 OK
C: DATA
S: 354 End data with <CR><LF>.<CR><LF>
C: [message body]
C: .
S: 250 Message accepted for delivery
C: QUIT
S: 221 Bye
Based on the SMTP protocol rules, which of the following statements is most accurate about this interaction?
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Correct answer: (D) The client successfully sent the message, but it will only be delivered to Carol, since Bob's address was rejected.
Which of the following is a default port number for FTP?
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Correct answer: (D) 21
In the ID3 (Iterative Dichotomiser 3) algorithm used for building Decision Trees, which of the following statements is correct?
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Correct answer: (B) ID3 selects the feature with the highest information gain at each node to reduce uncertainty.
Which of the following statements in Java will compile and execute successfully without violating keyword usage rules?
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Correct answer: (D) int _for = 5; System.out.println(_for);
Which of the following statements best characterises unsupervised learning in contrast to supervised learning?
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Correct answer: (B) It discovers inherent patterns in unlabeled data without predefined outputs.
In a multimedia operating system, which of the following functionalities is most critical to ensure continuous playback of audio and video streams without jitter or frame drops?
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Correct answer: (C) Real-time process scheduling with deadline constraints
Consider the following Java program:
class Demo {
int x = 5;
static int y = 10;
void display() {
int x = 20;
System.out.println(x + " " + this.x + " " + y);
}
}
class Test {
static int y = 50;
public static void main(String[] args) {
Demo d = new Demo();
d.display();
System.out.println(d.y + " " + y);
}
}
What will be the output of the program?
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Correct answer: (D) 20 5 10 and 10 50
In the process of converting a Moore machine to an equivalent Mealy machine, which of the following statements is true?
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Correct answer: (B) Mealy machine can produce outputs one input symbol earlier than the equivalent Moore machine.
In a neural network, which function introduces non-linearity?
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Correct answer: (A) Activation function
In an AND gate with two inputs A and B, the output Y is defined as Y=AB. Which of the following truth table entries correctly represents this logic?
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Correct answer: (C) A=1, B=1 → Y=1
What is called a textual, language-independent description of an algorithm used to plan and understand a solution?
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Correct answer: (B) Pseudocode
Which of the following assertions most accurately characterises the semantics of primitive data types as defined by the Java Language Specification?
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Correct answer: (D) The char data type in Java is a 16-bit unsigned integer representing Unicode characters.
A multimedia production team is developing an educational documentary that integrates narration, ambient sound, synchronised animations and live-action footage. The final output must maintain lip synchronisation, balanced audio mixing and seamless video transitions for both web streaming and broadcast-quality formats.
Which of the following production workflows ensures maximum synchronisation accuracy, audiovisual consistency and cross-platform compatibility?
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Correct answer: (B) Record video and audio separately, use a clapperboard or timecode for synchronisation, perform multi-track audio mixing and colour grading, then export using broadcast-safe codecs (e.g., MXF or ProRes) and adaptive web formats (e.g., MP4/H.264).
Which Unix System call is equivalent to Windows System call CreateFile()?
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Correct answer: (B) open()
Consider a DFS on a graph with vertices {A, B, C, D, E}.
If the traversal starts at A and discovers vertices in order A → B → C → D → E, what is the DFS finishing order?
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Correct answer: (B) E, D, C, B, A
Which of the following regular expressions defines an infinite language over the alphabet Σ = {a, b}?
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Correct answer: (B) (a+b)*
In the context of multimedia compositing, which of the following best describes the primary function of chroma keying used in live-action and post-production integration?
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Correct answer: (A) It isolates and removes a specific colour background to merge live-action footage with another visual element.
Which of the following is NOT a valid location for source or result operands in a computer system?
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Correct answer: (B) Control Unit buffer
Which of the following statements about domain constraints in a relational database is most accurate?
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Correct answer: (B) Domain constraints ensure that each attribute's value belongs to a predefined set or type, and may restrict NULL values if specified.
The instruction STA 3000H performs which of the following operations?
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Correct answer: (A) Stores accumulator data into memory location 3000H
Which of the following correctly matches a grammar type with its corresponding language and accepting device in the Chomsky Hierarchy?
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Correct answer: (C) Type 3 — Regular Grammar — Finite Automaton
A table Account is defined as:
CREATE TABLE Account (
AccNo INT PRIMARY KEY,
Balance DECIMAL(10,2) CHECK (Balance >= 500)
);
Which sequence of operations violates data integrity without violating entity integrity?
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Correct answer: (B) Updating balance to 200
What is the function of the control bus in a computer system?
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Correct answer: (D) To carry control signals
Which of the following identifiers is invalid in Java according to language rules?
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Correct answer: (D) 3DModel
Consider the following C program that creates and traverses a singly linked list. What will be the output?
#include <stdio.h>
#include <stdlib.h>
struct Node {
int data;
struct Node *next;
};
int main() {
struct Node *head, *second, *third;
head = (struct Node*)malloc(sizeof(struct Node));
second = (struct Node*)malloc(sizeof(struct Node));
third = (struct Node*)malloc(sizeof(struct Node));
head->data = 5;
head->next = second;
second->data = 10;
second->next = third;
third->data = 15;
third->next = NULL;
struct Node *ptr = head;
while (ptr != NULL) {
printf("%d ", ptr->data);
ptr = ptr->next->next;
}
return 0;
}
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Correct answer: (D) Segmentation fault (runtime error)
Which of the following statements about Software Engineering is most accurate according to its core principles?
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Correct answer: (A) Software Engineering emphasises systematic, disciplined and quantifiable approaches to software development, operation and maintenance.
Which of the following elements of graphic design primarily helps in creating depth, contrast and emphasis by controlling how light or dark an area appears?
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Correct answer: (A) Value
How to use these BEL PE Computer Science questions
Every question here was asked in a real BEL PE paper; the paper and shift are shown on the card, and the number opens the question on its own page. Try each one before tapping Show answer, then attempt the full BEL PE papers as timed tests to check your speed under exam conditions.