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Friday, August 28, 2026

Chapter 3: Computer Virus St Jude's High School class -7

Created by Bijan Krishna Paul

Chapter 3: Computer Virus

Section A: Multiple Choice Questions (30 Marks)

1. What does the acronym VIRUS stand for?

A) Very Important Resource Under System
B) Vital Information Resources Under Seize
C) Valuable Information Recovery Utility Software
D) Virtual Input Resources Under Scan

2. Which type of virus infects the Master Boot Record (MBR) and becomes active when the system starts?

A) Program File Virus
B) Boot Sector Virus
C) Macro Virus
D) Stealth Virus

3. Program File viruses target files with extensions such as:

A) .docx and .xlsx
B) .exe, .com, .sys, and .drv
C) .png and .jpg
D) .mp3 and .wav

4. A hybrid virus that infects both the boot sector and executable program files is called a:

A) Polymorphic Virus
B) Multipartite Virus
C) Network Virus
D) Stealth Virus

5. Which virus infects documents created in applications like Word, Excel, and PowerPoint that support automation macros?

A) Boot Sector Virus
B) Macro Virus
C) Trojan Horse
D) Worm

6. A polymorphic virus is known for its ability to:

A) Delete all hard drive partitions
B) Change its binary pattern every time it infects a file
C) Lock keyboard input
D) Display continuous printing jobs

7. The key difference between a computer worm and a virus is that a worm:

A) Cannot replicate
B) Is a self-replicating program that spreads without human action
C) Requires opening an email image
D) Only affects hardware monitors

8. Which malicious program tricks users by appearing as useful software at first glance but damages the system once installed?

A) Worm
B) Trojan Horse
C) Firewall
D) Macro

9. Malicious software that secretly monitors browsing habits, passwords, and user activities without knowledge is:

A) Spyware
B) Boot Virus
C) Firewall
D) Antivirus

10. Which fake program looks like an antivirus software and scares users into thinking their system is infected?

A) Sweeper
B) Norton
C) McAfee
D) AVG

11. The background scanning process in an antivirus that checks files continuously whenever opened or saved is called:

A) Real-time scan
B) Boot scan
C) Manual scan
D) Full system formatting

12. Isolating an infected file by an antivirus so it cannot affect the system is known as:

A) Formatting
B) Quarantining
C) Backing up
D) Defragmenting

13. What feature automatically launches installers and programs when a flash drive or CD is inserted?

A) AutoRun
B) Smart Scan
C) Task Manager
D) Disk Cleanup

14. The term 'Malware' is made up of which two words?

A) Malicious and Ware
B) Malicious and Software
C) Male and Share
D) Main and Hardware

15. What system utility controls incoming and outgoing network traffic to prevent unauthorized access?

A) Firewall
B) Disk Defragmenter
C) Web Browser
D) Control Panel

16. Which historical virus was first detected on ARPANET in the early 1970s?

A) Creeper Virus
B) Brain
C) Melissa
D) Elk Cloner

17. Which boot sector virus created in 1986 is recognized as the first PC virus?

A) Brain
B) Nimda
C) Zeus
D) Blaster

18. Which famous worm released on November 2, 1988 was among the first distributed over the internet?

A) Morris Worm
B) Blaster Worm
C) SQL Slammer
D) Beast

19. Why is regular updating of antivirus database files essential?

A) To clean the computer monitor screen
B) To detect and catch new types of virus threats
C) To increase internet speed double times
D) To delete original Windows system files

20. Network viruses rapidly spread through:

A) Local Area Networks (LAN) and shared drives/folders
B) Power extension cords
C) Unplugged monitors
D) Standard mouse pads

21. Rashmi inserted a friend's pen drive into her computer and found her files unreadable next day. What precaution did she skip?

A) Changing monitor brightness
B) Scanning the pen drive before opening files
C) Deleting the keyboard driver
D) Turning off system power

22. Which symptom indicates that a computer system might be virus affected?

A) Computer moving cursor on its own, restarting frequently, and unexpected error messages popping up
B) Monitor display turning crystal clear
C) Typing speed increasing automatically
D) Printer printing pages faster

23. An antivirus program contains two main components: scan engine and:

A) Graphic card
B) Virus database
C) Power cord
D) Web browser

24. Which of the following is NOT a genuine antivirus software?

A) Quick Heal
B) Bitdefender
C) Sweeper
D) Norton

25. Stealth viruses are difficult for antivirus software to detect because they:

A) Use various methods to avoid detection
B) Delete the CPU chip physically
C) Only attack printed paper
D) Run only when computer is powered off

26. Which destructive virus is considered to have caused an estimated financial damage of $52.2 billion?

A) MyDoom Virus
B) Brain
C) Cascade
D) Sunday

27. Trojan horses do not reproduce by infecting other files; instead they can create a:

A) Backdoor giving unauthorized access to malicious users
B) New boot sector partition
C) Document table
D) Spreadsheet macro

28. How often is it recommended to scan your computer hard disk as a preventive measure?

A) Once every 5 years
B) Twice a month
C) Every 5 seconds
D) Never

29. Which safety tip should be followed when dealing with email attachments?

A) Open all unknown executable (.exe) attachments immediately
B) Never click on an attachment unless it is from some genuine and trusted source
C) Share confidential passwords with unknown senders
D) Disable firewall when downloading attachments

30. Can Android phones get infected by viruses?

A) Yes, if users download apps from unsafe sources
B) No, smartphones are 100% immune
C) Only if placed near food
D) Only during phone calls

Section B: Assertion & Reason Questions (30 Marks)

Directions: Choose the correct option for each question:

  • A: Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • B: Both Assertion (A) and Reason (R) are true, but Reason (R) is NOT the correct explanation of Assertion (A).
  • C: Assertion (A) is true, but Reason (R) is false.
  • D: Assertion (A) is false, but Reason (R) is true.

31. Assertion (A): Updating antivirus software frequently helps protect the system against new virus threats.
Reason (R): Antivirus updates refresh the virus database with list of file patterns used to identify newly developed viruses.

32. Assertion (A): Computer worms require human action to travel and spread to other computers.
Reason (R): Worms are self-replicating programs that have the capability to spread without any human intervention.

33. Assertion (A): Trojan Horses appear at first glance to be useful software.
Reason (R): They trick users into opening or installing them, causing damage once installed.

34. Assertion (A): Boot sector viruses infect the first sector of a hard drive carrying the Master Boot Record (MBR).
Reason (R): Boot sector viruses become active at the time of booting the machine.

35. Assertion (A): Sweeper is a genuine antivirus program recommended for system cleanup.
Reason (R): Sweeper is a form of virus coming from malicious websites that looks like an antivirus program.

36. Assertion (A): Real-time scan runs continuously in the background of an antivirus.
Reason (R): It provides maximum protection by scanning opened or saved files and displaying security risk alerts.

37. Assertion (A): Macro viruses infect executable files ending in .exe and .com.
Reason (R): Macro viruses infect files created using application software that support Macros, like Word and Excel.

38. Assertion (A): Simply installing an antivirus software once guarantees 100% protection forever.
Reason (R): Installed antivirus software may not be able to detect any new virus programs unless frequently updated.

39. Assertion (A): Spyware monitors user activity without their knowledge.
Reason (R): Spyware collects personal information like surfing habits and passwords, transmitting it in the background.

40. Assertion (A): Quarantining a virus means deleting the file completely from the hard drive.
Reason (R): Quarantining isolates the virus so that it cannot affect the rest of the system.

41. Assertion (A): Disabling AutoRun on flash drives helps prevent automatic virus infections.
Reason (R): AutoRun automatically launches programs and installers as soon as a flash drive is inserted.

42. Assertion (A): Polymorphic viruses change their binary pattern every time they infect a file.
Reason (R): Changing binary patterns helps polymorphic viruses avoid detection by antivirus programs.

43. Assertion (A): A computer virus can make your physical screen crack like broken glass.
Reason (R): Viruses are software programs that disrupt software operations, memory, and data, not physical glass hardware.

44. Assertion (A): Installing a firewall is recommended to prevent virus and security attacks.
Reason (R): A firewall controls the incoming and outgoing network traffic on your system.

45. Assertion (A): A multipartite virus is classified as a hybrid virus.
Reason (R): It combines characteristics of both a Boot Sector virus and a Program File virus.

46. Assertion (A): Downloading pirated software from the internet is completely safe from virus infections.
Reason (R): Downloading pirated software can install malicious code, adware, or trojans onto your system.

47. Assertion (A): Network viruses multiply through shared resources like shared drives and folders.
Reason (R): When a network virus infects a computer, it searches through the network to attack new potential targets.

48. Assertion (A): Taking frequent backups of files is recommended for data safety.
Reason (R): Backups ensure that if data is lost or damaged due to a virus attack, original copies can be restored.

49. Assertion (A): Antivirus software should be turned off when making the computer work faster.
Reason (R): Turning off antivirus software removes protection and leaves the system vulnerable to virus attacks.

50. Assertion (A): Trojan Horses self-replicate rapidly across files just like worms.
Reason (R): Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self-replicate.

51. Assertion (A): The scan engine in an antivirus compares files with pattern files in the virus database.
Reason (R): Matching file patterns with known virus signatures verifies whether a file is infected.

52. Assertion (A): Malware is a generic term used only for useful system utility programs.
Reason (R): Malware is a generic term for malicious software that enters and damages a computer without user knowledge.

53. Assertion (A): Unexpected error messages and distorted menus indicate a virus affected system.
Reason (R): Virus infection disrupts normal system functioning and causes application malfunctioning.

54. Assertion (A): Email attachments ending with .exe should be opened directly without caution.
Reason (R): Executable file attachments in emails can contain viruses and mislead recipients into executing malware.

55. Assertion (A): Antivirus companies provide facilities to download latest updates from their websites.
Reason (R): Updating software ensures the system is armed and prepared against all latest virus threats.

56. Assertion (A): Computer worms often cause heavy consumption of system memory or network bandwidth.
Reason (R): The self-replicating nature of worms causes servers and individual computers to stop responding.

57. Assertion (A): Almost all viruses exist attached to executable files.
Reason (R): A virus will not infect the computer unless you run or open the malicious executable program.

58. Assertion (A): Always scanning a pen drive before using it prevents virus transmission.
Reason (R): Flash drives are a very common source through which infected data spreads between computers.

59. Assertion (A): The name Trojan Horse was derived from the wooden horse used by the Greek Army to conquer Troy.
Reason (R): Trojan Horse software appears useful at first glance, but damages the computer once installed.

60. Assertion (A): Protecting your computer and files from virus threat is a continuous on-going activity.
Reason (R): New viruses are constantly created, requiring continuous vigilance and updated software.

Section C: Image & Visual Feature Based Questions (10 Marks)

61. Identify the AVG Antivirus software interface step:
AVG Main Window ➔ [ Run Smart Scan ] button.
What happens when the user clicks 'Run Smart Scan'?

A) Initiates the scanning process to check files for viruses
B) Formats the hard drive completely
C) Installs new printer drivers
D) Turns off Windows security

62. Observe the pop-up notification visual upon plugging in a flash drive:
External drive connected ➔ [ Scan for Threats ]
Which action should be taken when this prompt appears?

A) Click 'Scan for Threats' to start scanning before opening files
B) Ignore warning and run setup files immediately
C) Delete all files on the drive
D) Disconnect the computer power cord

63. Identify the process sequence flowchart:
Virus Enters ➔ Virus Activates ➔ User Detects Problem ➔ Runs Antivirus ➔ System Restored
What action should be taken at the 'User Detects Problem' stage (noticing slow speed or crashes)?

A) Run an antivirus scan, remove virus, and update software
B) Turn off the computer permanently
C) Click on all pop-up ads
D) Re-type the whole document

64. Scenario Visual: Mohit receives security alert pop-ups displaying a list of fake malware files prompting him to buy software. What fake antivirus threat is displaying these fake alerts?

A) Sweeper
B) Microsoft Security Essentials
C) AVG Antivirus
D) Quick Heal

65. Look at the antivirus action options after scanning:
Virus Found: [ Delete ] | [ Quarantine ]
What does selecting 'Quarantine' do?

A) Isolates the virus so that it cannot affect the system
B) Sends the file to a friend
C) Installs new memory
D) Turns off real-time scan

66. Scenario Visual: Rashmi opens an infected Word document containing step-by-step automated actions. Which type of virus gets loaded into main memory when this document opens?

A) Macro Virus
B) Boot Sector Virus
C) Hardware Fault
D) Serial Port Error

67. Identify the classification category diagram:
Malware ➔ [ Worms | Trojans | Spyware | Sweeper ]
Which type specifically snoops chat programs, scans hard drives, and transmits surfing habits to third parties?

A) Spyware
B) Boot Virus
C) Sound Card
D) Motherboard

68. Scenario Visual: Mohit notices his computer cursor moving all by itself and windows opening and closing randomly. What does this symptom indicate?

A) The system is virus affected
B) The computer has extra power
C) Monitor resolution is low
D) Keyboard needs cleaning

69. Look at the email attachment visual:
From: Unknown Sender
Attachment: PrizeWin.exe
What is the proper precautionary step?

A) Never click on the attachment unless from a genuine and trusted source
B) Double-click the .exe attachment immediately
C) Forward it to all friends
D) Disable the antivirus software

70. Identify the component description:
"A security software mechanism installed on a system to control incoming and outgoing network traffic." What is it?

A) Firewall
B) Monitor
C) CPU Clock
D) RAM Chip
Created by Bijan Krishna Paul

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