Punjab School Education Board

Class 9 Computer Science (2025-26)

Dear students. In this article, you can practice of all the lessons of computer science of Class 9. You can note the exercise of these lessons by clicking on the links of the relevant lessons given below.

    Computer Science

    Class :- 9th

    Lesson – 1 Networking

    Multiple Choice Questions.

    1. ________________ is a group of two or more computers, which are connected together to share resources, such as printers, files, etc.

    A. Network     B. Internet     C. Wireless     D. Topology

    2. Which of the following is the smallest network?

    A. WAN     B. MAN     C. LAN     D. None of these

    3. ________ is a device that allows you to connect multiple computers to a single network device.

    A. Hub     B. Bus     C. Ring     D. Star

    4. ________ In a network topology, a single backbone cable is shared by all the devices.

    A. Bus     B. Tree     C. Mesh     D. Star

    5. _______ generates and sends information.

    A. Protocol     B. Receiver     C. Sender     D. Hub

    Tell me True False.

    1. We cannot share hardware or software in network devices. (False)

    2. A network covers a large geographical area. (False)

    3. Information can be transmitted in both directions in full duplex. (True)

    4. A protocol is a set of rules according to which data is transmitted between nodes. (True)

    Write the full forms.

    1. LAN : Local Area Network

    2. MAN : Metropolitan Area Network

    3. WAN : Wide Area Network

    4. PAN : Personal Area Network

    5. NIC : Network Interface Card

    Short Answer Questions.

    Question 1. Name any four network topologies?

    Answer. The names of the four network topologies are as follows:

    1. Ring topology

    2. Bus topology

    3. Star topology

    4. Tree topology

    5. Hybrid topology

    Question 2. Define Network Interface Card (NIC)?

    Answer. A network interface card is a computer circuit board or card that connects a computer to a network. It is present in every client and server computer. This card establishes a connection between the server and the client. There are two types of network interface cards: Ethernet card and wireless card.

    Question: 3. Write the names of the components of data communication?

    Answer: Names of the components of data communication:-

    1.        Sender: Sender prepares and forwards the information.

    2.        Medium:- It carries the information from the sender to the receiver.

    3.        Receiver: Receiver receives the information.

    4.        Protocols: These are the rules through which data is transmitted between the sender and the receiver.

    Question: 4. Write a note on hub?

    Answer: A networking hub is a device that allows you to connect more than one computer to a network device. A hub duplicates the data received from one port and makes it available on all the ports. A hub also allows data to be distributed among all the devices connected to it.

    Question: 5. What are the two types of ring topology?

    Answer: There are two types of ring topology:

    1. Single ring:- In a single ring network, a single cable is shared by the computer network and the data goes in one direction. Each device waits its turn and forwards this data. Until the data reaches its destination, no other device can send data.

    2. Dual Ring:- This topology uses two types of rings to send data in different directions so that more packets can be sent over the network.

    Long answer questions.

    Question: 1. What is a network? Write the advantages and disadvantages of a network.?

    Answer:- A network is a collection of two or more computers that are interconnected through wires, telephone lines, radio waves, satellites or infrared waves in a network, so that files can be exchanged, resources can be shared. Through a network, software and hardware resources can be shared among many users. Network connections in computers are made through cable wires, but network connections can also be made through radio signals, telephone, telephone wires or other long-distance satellite links.

    Advantages of networks:-

    1. Data and information can be shared with networks.

    2. Hardware and software can be shared through networks.

    3. Communication can be done very fast through networks.

    4. Files can be accessed and shared quickly through networks.

    5. Through networks, we can reduce the cost of the entire system by sharing expensive input and output devices like printers.

    6. The network ensures the use of many resources.

    7. It is easy to take backup from the server while connected to the network.

    8. The network also provides security.

    9. It is easy to share and transfer files through the network.

    Disadvantages of networks:-

    1. When the network fails, all the central facilities fail.

    2. Managing the network is a difficult task.

    3. Security risks are always present on the network. There can also be misuse of data on the network.

    4. Building a network is an expensive business

    5. Cables and hardware are difficult to purchase and replace.

    Question: 2. Describe the different parts of a computer network?

    Answer: There are many parts of a computer network. Each part is essential for the smooth functioning of the network. The various main parts of a computer network can be explained as follows:

    1. Computer: The main function of a network is to connect computers to each other. These computers for a network are of the following two types.

    a. Client or node: It is a simple computer system. It is connected to the network to share resources in the network.

    b. Server: It is a powerful computer. It helps in sharing information or resources in the network. It controls the client computers in the computer network.

    2. Network Interface Card (NIC): The network interface card is a computer circuit board or card that connects the computer to the network. It is present in every client and server computer. This card connects the server and the client. There are two types of network interface cards: Ethernet cards and wireless cards.

    3. Hub/Switch: A networking hub is a device that allows you to connect more than one computer to a network device. A hub duplicates the data received from one port and makes it available on all the ports. A hub also allows data to be distributed among all the devices connected to it.

    4. Router: A router is a hardware device that receives data, monitors it, and forwards that data within the same network or to other networks. With the help of a router, data is sent in the form of packets.

    Question: 3. Write about different types of networks?

    Answer: There are many types of networks. Networks can be divided into different categories according to their size and the way they are used. Based on the size of the network, they can be divided into the following four categories:

    1. PAN: The full name of PAN is Personal Area Network. This network is located around a building or a single person. It can be inside a small office or residence. A personal network is made of cables or wireless. It is the interconnection of gadgets such as laptops, computers, cellphones, printers, etc. This network is within a radius of 10 meters of the user. This network includes various connections such as Ethernet, Ethernet, Bluetooth, etc. It is used by a single person.

    2. LAN: The full name of LAN is Local Area Network. It is used to communicate between computer devices. Local area means one's own home, school, business organization, college, a room, etc. This network can be in Through this network we can share many resources like files or hardware devices. This network is not spread far, it is limited to a few places. The range of this network is less than 1 mile and the data speed is from 10Mbps to 10Gbps.

    3. MAN:- The full name of MAN is Metropolitan Area Network. This network is distributed in big cities, college campuses, and large areas through cable TV networks. Many LAN networks are combined to form a LAN, and it is used in a large geographical area. MAN network covers an area of ​​10km to 80-90km. Big business firms in cities use this network to stay connected with their small branches. It costs a lot to build such a network.

    4. WAN: The full name of WAN is Wide Area Network. This is a very large network, it is neither limited to any building nor any city. It works to connect the entire world network. WAN network consists of many small networks, such as LAN and MAN network. Through this network, we can send and receive data securely. The best example of WAN network is the Internet, through which we can communicate with any of our distant relatives through video call, audio call, text message through the Internet.

    Question: 4. Describe the different modes of data transmission?

    Answer: Data transmission means the flow of data or information between the sender and the receiver. The flow of data or information between the sender and the receiver can be done in many ways. These methods can be of 3 types as follows:

    1. Simplex:- In simplex, the data transmission is unidirectional, i.e. information can go in only one direction. Only one of the two connected devices can transfer data and the other can receive data. Example: Keyboard, Mouse, Television.

    2. Half Duplex:- In half duplex, data transmission takes place between two devices, i.e. both the sender and the receiver can send data to each other, but in only one direction at a time. This transmission is used when there is no need for data transmission at the same time. Example: Walkie-Talkie

    3. Full Duplex:- Through full duplex, both the sender and the receiver can transmit data at the same time. In full duplex, the data transmission capacity is divided into two parts so that both can transmit data. Example: Telephone line.

     

    Lesson – 2 Internet Applications

    Multiple Choice Questions.

    1. Gmail is a free e-mail service provided by ____.

    a. Yahoo b. Google c. Rediffmail d. Hotmail

    2. In computing, ____ is a type of test used to determine whether the user accessing a webpage is human or not

    a. CAPTCHA b. DERTSA c. HEPTCHA d. NEPHCA

    3. ____ is a type of malware designed to provide unauthorized remote access to a user's computer.

    a. Spyware b. Trojan c. Malware d. Horse

    4. ____ is a computer program that replicates itself into other computer programs.

    a. Spyware b. Virus c. Phishing d. Malware

    5. _______ is an Indian digital literacy online service provided by the Ministry of Electronics and Information Technology, Government of India under the Digital India initiative.

    A. DigiLocker B. DigiProgram C. DigiHacker D. DigiBanker

    Write True False.

    1. Spyware is a method of email fraud, in which a fraudster sends legitimate-looking emails in an attempt to collect personal and financial information. (False)

    2. Google Drive does not allow us to store and share files online. (False)

    3. The best way to deal with the threat of computer viruses is to use antivirus software. (True)

    4. Internet threats can be any threats that use the World Wide Web for cybercrime. (True)

    5. Google Meet is a video conferencing service provided by Google. (True)

    Short answer questions.

    Question: 1. Define email?

    Answer: Email is a complete electronic mail, it is one of the most used features on the internet. It allows us to send and receive messages to anyone anywhere in the world using an email address. Any document like pictures, messages, audio, videos, notes etc. can be sent and received through email within minutes.

    Question: 2. Name any four Google apps?

    Answer: The names of the four Google apps are as follows:-

    1. Google Docs

    2. Google Translate

    3. Google Maps

    4. Google Meet

    5. Google Lens

    Question: 3. Define cyber ethics?

    Answer: Cyber ​​ethics refers to the acceptable use of online resources and responsible behavior by a user, how we use the internet properly, understanding our responsibilities. Users should ensure that they understand their responsibilities while working online, and respect the rights and property of others on the internet.

    Question: 4. What is DigiLocker?

    Answer: DigiLocker is an Indian digitalization online service, provided by the Ministry of Electronics and Information Technology, Government of India under the Digital India initiative. DigiLocker provides an account on the cloud to every Aadhaar holder to provide access to authenticated documents or certificates such as driving license, vehicle registration, academic marksheets, etc. in digital format from the original issuers of the certificates. DigiLocker provides 1 GB of storage space to each account holder to upload scanned copies of documents.

    Question: 5. What is cloud printing?

    Answer: When we store data in our mobile or computer on Google Cloud like Google Drive, that data gets stored on Google's server and we can also print that data. To take a print of the data present in Google Cloud, we have to connect our device to the printer, for this we can connect it through USB cable or Wi-Fi or Bluetooth and take a print of the data present in Google Cloud Print.

    Questions with long answers.

    Question: 1. What are Google Apps? Describe any two Google apps?

    Answer: A group of some web-based applications of Google is called Google Apps. These apps include email, calendar, maps, word-processing etc. Their description is as follows:

    1. Gmail: This Google app is used to send or receive emails. With this, we can send messages to anyone through the internet from a computer or mobile. It is necessary to have a Google account to use this app.

    2. Google Drive: This Google app is used to store data on an online drive. Google provides 15 GB of memory to each account to store data online. It is necessary to have a Google account to use this app.

    3. Google Map: This Google app is used to view maps of any place in the world. We can also get information about our current location through GPS technology. It also provides navigation facilities with which we can easily reach from one place to another.

    Question: 2. What is Google Drive? What are the benefits of Google Drive?

    Answer: Google Drive is a service offered by Google, through which we can store and share files online, and this service was launched on 24 April 2012. Google Drive gives us 15GB of free storage space, and additional storage can be purchased for a monthly fee. Its main benefits are as follows:

    1. In Google Drive, we can store our data on an online drive.

    2. We can share the files stored on Google Drive with other people.

    3. We can view the files stored on Google Drive from anywhere.

    4. We can easily find the files stored on Google Drive because it also provides us with a built-in search engine.

    5. Google Drive also provides the facility of optical character recognition.

    6. In Google Drive, we can open and view various types of files (pdf, jpg, jpg, etc.).

    7. All these facilities are provided free of cost by Google.

    Question: 3. Write about the different methods of internet security?

    Answer: The different methods of internet security are as follows:-

    1. Antivirus:- It is a software or program, which is used to detect and delete viruses in the computer. Apart from deleting viruses, antivirus also prevents worms, Trojans, and adware from entering the computer. Antivirus software scans our online activities and ensures that we are not downloading any infected files. In case of a virus in the computer, we can identify it with the help of antivirus and also destroy it.

    2. Antispyware:- It is a software or program that is effective in finding and eliminating unwanted spyware programs. Spyware programs are difficult to eliminate because whenever we eliminate them from the programs, these programs reinstall themselves. To combat spyware, we need to use a dedicated spyware management tool. Some antivirus software already includes spyware management tools.

    3. Prevention from Trojan Horses:- To keep our system safe from Trojan horses, we should never download or install software from a source that we do not trust. We should never open email attachments or programs received from unknown or untrusted sources. To protect our system from Trojans, we should also ensure that our computer has a valid antivirus installed, so that Trojan horses can be prevented.

    4. Prevention of Phishing Scams: - We should avoid clicking on links or file attachments received through emails to protect ourselves from phishing scams. Data or files should be downloaded only by logging in to an official website. Be sure to use antivirus software in your computer, antivirus software blocks fake emails, messages. Keep all the software you are using in your computer updated and always use licensed software.

    Question: 4. What are cybercrimes? Write measures to prevent cybercrime?

    Answer: Cybercrime is a crime in which a computer, network device or network is used to commit a crime. Cybercrime is not always done by individuals or hackers, but is also done by organizations, cybercrime can endanger the security and financial health of an individual or a country. Cybercrime is an illegal act in which a computer can be used either as a tool or as a target or for both purposes to commit a crime. Any crime that causes harm to the honor or physical harm of a person or groups of people through electronic means is called cybercrime.

    Measures to prevent cybercrime:-

    1. Never use your internet banking and banking transactions in a public cyber cafe or in a crowded area, where your personal information can be easily stolen.

    2. Never do any kind of transaction under internet banking on another person's computer and do not forget to log out of your email account after making the transaction, and also delete such data from the browser history.

    3. After logging in to any account, we should not click on the options asked by the computer such as keep on logging in or remember password link.

    4. We should not open any spam message received in the in-box of our email account nor should we download the attached file.

    5. We should keep our computer updated with software like antivirus and antimalware to protect our computer from computer virus attacks.