Computer Science · Sample Paper 1

General instructions

Section A · Objective

1. Question 11 mark

   The number of rows in a relation is called its

   1. A.degree
   2. B.cardinality
   3. C.domain
   4. D.schema
2. Question 21 mark

   A key that refers to the primary key of another table is a

   1. A.candidate key
   2. B.foreign key
   3. C.alternate key
   4. D.composite key
3. Question 31 mark

   The time complexity of binary search is

   1. A.O(n)
   2. B.O(log n)
   3. C.O(n²)
   4. D.O(1)
4. Question 41 mark

   Which block always executes whether an exception occurs or not?

   1. A.try
   2. B.except
   3. C.else
   4. D.finally
5. Question 51 mark

   int('abc') raises

   1. A.TypeError
   2. B.ValueError
   3. C.NameError
   4. D.KeyError
6. Question 61 mark

   Which mode opens a file for appending?

   1. A.'r'
   2. B.'w'
   3. C.'a'
   4. D.'x'
7. Question 71 mark

   Which module is used to write Python objects to a binary file?

   1. A.csv
   2. B.pickle
   3. C.os
   4. D.json
8. Question 81 mark

   A stack follows the principle

   1. A.FIFO
   2. B.LIFO
   3. C.FILO only for queues
   4. D.random access
9. Question 91 mark

   The postfix form of A + B * C is

   1. A.A B + C *
   2. B.A B C * +
   3. C.
      • A * B C
   4. D.A B C + *
10. Question 101 mark

    In a queue, deletion takes place at the

    1. A.rear
    2. B.front
    3. C.middle
    4. D.both ends
11. Question 111 mark

    In the worst case, bubble sort on n elements takes

    1. A.O(n)
    2. B.O(n log n)
    3. C.O(n²)
    4. D.O(log n)
12. Question 121 mark

    Binary search requires the list to be

    1. A.unsorted
    2. B.sorted
    3. C.of even length
    4. D.of strings
13. Question 131 mark

    Which SQL command removes a table along with its structure?

    1. A.DELETE
    2. B.DROP TABLE
    3. C.REMOVE
    4. D.TRUNCATE ROWS
14. Question 141 mark

    Which clause filters groups formed by GROUP BY?

    1. A.WHERE
    2. B.HAVING
    3. C.ORDER BY
    4. D.LIKE
15. Question 151 mark

    SELECT COUNT(*) FROM emp WHERE name LIKE 'A_%'; matches names that

    1. A.end with A
    2. B.start with A and have at least 2 characters
    3. C.have A as second letter
    4. D.are exactly 'A'
16. Question 161 mark

    Which device connects different networks and routes packets?

    1. A.hub
    2. B.switch
    3. C.router
    4. D.repeater
17. Question 171 mark

    Which topology has every node connected to a central device?

    1. A.bus
    2. B.ring
    3. C.star
    4. D.mesh
18. Question 181 mark

    Which protocol is used to send email?

    1. A.FTP
    2. B.SMTP
    3. C.HTTP
    4. D.PPP
19. Question 191 mark

    Malware that encrypts files and demands payment is

    1. A.worm
    2. B.trojan
    3. C.ransomware
    4. D.adware
20. Question 201 mark

    Assertion (A): Optical fibre is preferred for long-distance, high-speed communication.

    Reason (R): Optical fibre carries data as light and is immune to electromagnetic interference.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
21. Question 211 mark

    Assertion (A): A deque can be used as both a stack and a queue.

    Reason (R): Insertion and deletion are allowed at both ends of a deque.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.

Section B · Very short answer

1. Question 222 marks

   Differentiate between a candidate key and a primary key with an example.

2. Question 232 marks

   Write the output:

   try:
       x = 10 / 0
   except ZeroDivisionError:
       print('Divide by zero')
   else:
       print('OK')
   finally:
       print('End')
   

3. Question 242 marks

   Write a function count_lines() that counts the lines in a text file notes.txt that start with 'T'.

4. OR

   Question 242 marks

   Differentiate between text files and binary files (two points).

5. Question 252 marks

   Evaluate the postfix expression using a stack, showing the stack after each step: 5 3 + 2 *

6. Question 262 marks

   Differentiate between DDL and DML commands with one example each.

7. Question 272 marks

   Expand: (i) URL (ii) DNS (iii) MAC (iv) PAN.

8. Question 282 marks

   What is a firewall? Give two ways to protect a computer from malware.

Section C · Short answer

1. Question 293 marks

   Write functions push(stack, item) and pop(stack) for a stack implemented as a list. pop should print 'Underflow' if the stack is empty.

2. Question 303 marks

   Show the steps of binary search for 42 in [5, 11, 17, 23, 31, 42, 56].

3. OR

   Question 303 marks

   Show the list after each pass of bubble sort on [7, 3, 9, 1].

4. Question 313 marks

   Write a program to append a student's [roll, name, marks] record to student.dat using pickle, and a function to display all records.

Section D · Long answer

1. Question 324 marks

   Consider the table EMP:

   | EmpNo | Name | Dept | Salary | |---|---|---|---| | 1 | Asha | HR | 40000 | | 2 | Ravi | IT | 60000 | | 3 | Meena | IT | 55000 | | 4 | Karan | Sales | 35000 | | 5 | Neha | HR | 45000 |

   Write SQL queries to:

   (i) display names of employees in IT;

   (ii) display the average salary of each department;

   (iii) increase the salary of HR employees by 10%;

   (iv) display departments whose maximum salary is above 50000.

2. Question 334 marks

   Write a program to read items.csv (columns: item, qty, price) and print the item with the highest total value (qty × price).

3. OR

   Question 334 marks

   Write functions to implement a queue using a list: enqueue, dequeue (print 'Empty' if needed) and display.

4. Question 344 marks

   Write Python code to connect to a MySQL database school and display all rows of the table student whose marks are above 80.

5. Question 354 marks

   Explain four network devices with their functions.

Section E · Long answer

1. Question 365 marks

   Network design. A company has four blocks: Admin (40 computers), Finance (25), HR (15) and Store (10). Distances: Admin–Finance 60 m, Admin–HR 120 m, Admin–Store 50 m, Finance–HR 80 m, HR–Store 150 m.

   (i) Suggest the most suitable block for the server, with a reason. (1 mark)

   (ii) Suggest a cable layout connecting the blocks. (1 mark)

   (iii) Where would you place a repeater? (1 mark)

   (iv) Which device would you place in every block? (1 mark)

   (v) Which type of network (PAN, LAN, MAN, WAN) is formed? (1 mark)

2. Question 375 marks

   Write a program that keeps asking for two integers and prints their quotient. Handle ValueError (non-integer input) and ZeroDivisionError with suitable messages; stop when the user enters 'q'.

3. OR

   Question 375 marks

   Explain equi-join and natural join with an example using tables STUDENT(RollNo, Name, ClassID) and CLASS(ClassID, Teacher). Write a query to show each student's name with their teacher.