Computer Science: Model Question Sets and Predicted Questions

1. (a) — the station sends and viewers only receive.

2. (c) — a router joins networks and is the way out of the LAN.

3. (b) — each octet must be 0–255, and (d) is an IPv6 address.

4. (b) — ALTER TABLE … ADD changes the structure.

5. (b) — UNIQUE forbids repeats but allows NULL; a primary key allows neither.

6. (a) — GIF stores simple animation.

7. (b) — a pixel is one picture element.

8. (b) — / always gives a float, here 4.0.

9. (a) — int("abc") raises ValueError.

10. (a) — the training data are labelled.

11. A LAN covers a small area such as a room, building or campus; a WAN covers a country or the whole world. A LAN is owned by one organisation and is very fast; a WAN uses links of many organisations and is slower with more delay.

12. 900 MB × 8 = 7,200 Mb; 7,200 ÷ 30 = 240 s = 4 minutes.

13. A foreign key is a field in one table that refers to the primary key of another table, linking the two. Example: roll in marks(roll, subject, marks) refers to roll in students, so marks can be stored only for existing students.

14. WAV is uncompressed, so it keeps the exact recording but makes large files; MP3 is compressed (lossy), so files are about ten times smaller with slight loss of quality. WAV is used for recording and editing, MP3 for sharing and playing.

15.

def cube(n):
    return n ** 3

print(cube(4))

Output: 64.

16. range(5, 0, -2) counts down from 5 in steps of 2 and stops before 0: output 5 3 1.

17. Closing saves any data still in memory to the disk and frees the file for other programs. f = open("marks.txt", "a").

18. Generative AI is AI that creates new content — text, images, music, video or code — from a prompt. Tools: ChatGPT and Gemini (also Copilot, DALL·E).

19. On-demand access from anywhere over the Internet; scalability — resources grow or shrink as needed (also pay-as-you-go, automatic backup and updates).

20. AR adds digital images or information on top of the real world seen through a phone or glasses. In education, pointing a phone at a textbook picture can show a 3D model of the heart or the solar system.

21. Star: every computer is joined by its own cable to a central switch (sketch: a switch with computers around it); one faulty cable affects only one computer and faults are easy to find, but if the switch fails all stop. Mesh: computers are joined by many links, in a full mesh each to every other (sketch: five computers with all ten links); data has other paths if one fails, but it needs n(n−1)/2 cables — 780 for 40 computers. For a 40-computer lab choose the star: one 48-port switch and 40 cables are cheap, easy to install and easy to troubleshoot.

22.

CREATE TABLE products (
    pid   INT PRIMARY KEY,
    pname VARCHAR(30) NOT NULL,
    price DECIMAL(8, 2),
    stock INT DEFAULT 0
);
INSERT INTO products (pid, pname, price, stock) VALUES (6, 'Pencil box', 180, 25);
SELECT pname, price FROM products WHERE price BETWEEN 100 AND 500 ORDER BY price;
DELETE FROM products WHERE stock = 0;

With five more products in the table, the SELECT returned Notebook 120.00, Pencil box 180.00, Geometry box 280.00 and Water bottle 350.00, and the DELETE removed the water bottle (stock 0): 1 row affected.

23. Animation is the illusion of movement created by showing slightly different pictures quickly one after another (1). 2D animation is flat (width and height) and usually drawn; 3D animation has depth and is modelled, rigged and rendered, needing more time and computing power (2). In keyframe animation the animator sets only the key positions and the software calculates the in-between frames (tweens) (1).

24. (a) Four marks (45, 78, 90, 66) are 40 or more: output Passed: 4. (b)

marks = [45, 78, 32, 90, 66]
count = 0
total = 0
for m in marks:
    if m >= 40:
        count += 1
        total += m
print("Passed:", count)
print("Average of passed students:", total / count)

Passed: 4
Average of passed students: 69.75

25. IoT is the network of everyday objects fitted with sensors, software and Internet connections that collect and share data and act on it (1). Components: sensors, a microcontroller or device, a network connection, a cloud server, an app and actuators (1). Smart-city applications: traffic lights that adjust to the number of vehicles, reducing jams; street lights that dim or switch off when roads are empty, saving electricity (also full-bin alerts, smart parking) (1 + 1).

1. (c) — fibre carries light.

2. (b) — the Dynamic Host Configuration Protocol.

3. (a) — devices around one person form a PAN.

4. (b) — names are text of varying length.

5. (b) — DESC means descending, Z to A.

6. (b) — 1920 × 1080 is Full HD; 1280 × 720 is HD.

7. (a) — Audacity is a free audio editor.

8. (b) — pd.read_csv("file.csv").

9. (b) — the fill colour is applied between them.

10. (c) — ready software used online is SaaS.

11. A protocol is a set of rules that devices follow to communicate over a network. HTTP/HTTPS transfers web pages; SMTP sends email (also DHCP, DNS, FTP).

12. It joins different networks, such as a LAN and the Internet; and it chooses the best path for each packet using IP addresses (also NAT, DHCP and firewall in a home router).

13.

SELECT * FROM employee WHERE name LIKE '%sh';

On four sample rows it returned Ramesh and Mahesh.

14. Resolution is the number of pixels in an image, width × height, such as 1920 × 1080. More pixels show more detail but need more storage: an uncompressed 24-bit image needs width × height × 3 bytes, so doubling both width and height makes the file four times bigger.

15.

n = int(input("Enter a number: "))
if n % 2 == 0:
    print(n, "is even")
else:
    print(n, "is odd")

With 17: 17 is odd; with 24: 24 is even.

16.

try:
    n = float(input("Enter a number: "))
    print("100 divided by", n, "is", 100 / n)
except ZeroDivisionError:
    print("Cannot divide by zero.")

With 8: 100 divided by 8.0 is 12.5; with 0: Cannot divide by zero.

17. import math loads the whole module, so its functions are called with the module name: math.sqrt(49). from math import sqrt loads only sqrt, which is then called directly: sqrt(49). Both give 7.0.

18. Bias — a hiring system trained mostly on men's CVs may reject women; privacy — face-recognition cameras may record people without their consent (also security: a hacked self-driving car).

19. e-Commerce is buying and selling over the Internet, e.g. Daraz; e-governance is the government giving services and information online, e.g. the Nagarik App or online passport applications.

20. A robot is a programmable machine that senses its surroundings, decides and acts. In hospitals: robot-assisted surgery with tiny precise movements; and delivering medicines or disinfecting rooms (also helping patients move).

21. Guided media are communication media that carry signals along a physical cable (1). Types: twisted pair (pairs of copper wires twisted to reduce interference; CAT6 in LANs), coaxial cable (copper core, insulator, braided shield; cable TV, CCTV) and optical fibre (light in a glass core; ISP backbones) (1). Differences: twisted pair carries electrical signals and is limited to 100 m per run, while fibre carries light for tens of kilometres; twisted pair is cheap and easy to fit but affected by interference, while fibre is costlier but immune to electrical noise and much faster (2).

22. A relationship is a logical link between two tables through a common key field (1). One-to-many: one record in the first table matches many in the second, each of which matches only one — e.g. one teacher teaches many classes (1).

CREATE TABLE teachers (tid INT PRIMARY KEY, tname VARCHAR(40) NOT NULL);
CREATE TABLE classes (
    class_id VARCHAR(5) PRIMARY KEY,
    room     VARCHAR(10),
    tid      INT,
    FOREIGN KEY (tid) REFERENCES teachers(tid)
);

Tested: classes 9A, 10A (both teacher 1) and 10B (teacher 2) were accepted, and a class for a non-existent teacher 7 was refused with error 1452 (2).

23. WAV: 44,100 × 16 × 2 × 120 = 169,344,000 bits; ÷ 8 = 21,168,000 bytes ≈ 21.2 MB (2). MP3: 192,000 × 120 = 23,040,000 bits; ÷ 8 = 2,880,000 bytes ≈ 2.9 MB (1). Upload the MP3: about seven times smaller, so it loads and streams quickly, with quality that is very close to the original (1).

24. (a)

    Name  Age  Marks
0    Ram   15     72
2  Gopal   15     54

(b)

print(df[df["Marks"] > 80][["Name", "Marks"]])

   Name  Marks
1  Sita     88
3  Rita     91

25. IaaS provides virtual servers, storage and networks that the user's IT staff manage, e.g. Amazon EC2; PaaS provides a ready platform to build and run applications, e.g. Google App Engine; SaaS provides complete applications used online, e.g. Google Docs and Gmail (3). To share notes the school should use SaaS such as Google Drive or Google Classroom: nothing to install, students open the notes on any device, and the provider handles storage and backup (1).