MODEL QUESTION SOLUTION

 COMPUTER SCIENCE

ACCORDING TO CDC 2077

MODEL QUESTION SOLUTION

CLASS: 11                                                                                           FULL MARK: 50

TIME: 2 HOURS

 

Group A: Multiple Choice Questions Tick the best alternative.   (9 x 1=9)

1. Which one of the following is an input device?

      a) speaker          b) printer                          c) monitor          d) mouse

 

2. Which of the following is NOT a bus type?

      a) Address bus    b) Data bus       c) Memory bus  d) Control bus

                         

3. How to represent Boolean F(x,y)=x.y in logic gate?

 

 

 

Ans: a)

 

4. Which scheduling algorithm allocates the CPU first to the process that requests the CPU first?

     a) first-come, first-served scheduling             c) shortest job scheduling  

     b) priority scheduling                                             d) Round robin scheduling

 

5. Which operator is used to start for enter the formula in Excel cell?     

     a) $                                 b) @                              c) =                                       d) +

 

6. Which looping process checks the test condition at the end of the loop?    

     a) for                            b) while                        d) do-whiled         e) Nested loop

 

7. How to insert an image in web page using HTML tag?
    a) <img=...>                b) <img source..>       c) <img src=...>   d) <img href=..>

 

8. Which image format is best used for photographs and offers a small file size?(U)

     a) PNG                           b) GIF                         c) BMP                           d) JPEG

 

9. Which of following is monitors user activity on internet and transmit that information in the background to someone else? (U)

    a) Malware                  b) Spyware                c) Adware                   d) Virus

 

                                                 Group 'B'
Give short answer to the following questions.             (5 x 5=25)

1. Explain different types of secondary memory of computer system.

 Ans:

     Secondary memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing data/Information permanently. CPU directly does not access these memories instead they are accessed via input-output routines. Contents of secondary memories are first transferred to main memory, and then CPU can access it. The types of secondary memory are below:

1.     Magnetic Disk

2.     Floppy Disk

3.     Hard Disk

4.     Optical Disks

Magnetic Disk: The Magnetic Disk is Flat, circular platter with metallic coating that is rotated beneath read/write heads. It is a Random access device; read/write head can be moved to any location on the platter.

Floppy Dis: These are small removable disks that are plastic coated with magnetic recording material. Floppy disks are typically 3.5″ in size (diameter) and can hold 1.44 MB of data. This portable storage device is a rewritable media and can be reused a number of times. Floppy disks are commonly used to move files between different computers.

Hard Disk: Another form of auxiliary storage is a hard disk. A hard disk consists of one or more rigid metal plates coated with a metal oxide material that allows data to be magnetically recorded on the surface of the platters.

                                                     OR

    Describe the decimal to binary number conversion process with example.

Ans:

      A decimal number has base 10 and a binary number has base 2. In decimal to binary conversion, the base of the number also changes, i.e. from base 10 to base 2. All the decimal numbers have its equivalent binary numbers. These binary numbers are majorly used in computer applications, where it is used for programming or coding purpose. This is because computers understand the language of binary digits, o and 1.

Hence, once we give the input to the computer system in the decimal form, it converts them into binary digits, performs the required operations and provides the output with into decimal form again. Now, learn here how the decimal number can be represented here in binary form. But before learning the steps for conversion, first, let us see the table to know the equivalent binary number for a decimal number.

 

2. What are the functions of operating system? Describe.

   Ans:

         The functions of operating system are below:

a.     I/O management :

b.     Command interpreter;

c.      Data management;

d.     Memory Management;

e.     Process management;

f.       Devices management;

g.     File management;

h.     Time sharing;

Some of them are mention below

1.     Processor Management — The OS (Operating System) ensures that each process/application receives enough time from the processor to function properly. It also tries to utilize as many processor cycles as possible for the real time work.

2.     Memory Storage and Management — The OS (Operating System) manages the sharing of internal memory among the multiple applications. It also ensures that one process should not consume the memory allocated to another process. An OS has to make efficient utilisation of different types of memory (RAM, Cache, etc.) within the system, so as to ensure proper execution of every process.

3. Define different types of CSS.

Ans:

     Cascading Style Sheet (CSS) is used to set the style in web pages that contain HTML elements. It sets the background color, font-size, font-family, color,… etc property of elements on a web page. There are three types of CSS which are given below: 

 

·         Inline CSS

·         Internal or Embedded CSS

·         External CSS

 

Inline CSS: Inline CSS contains the CSS property in the body section attached with element is known as inline CSS. This kind of style is specified within an HTML tag using the style attribute. 

 

Internal or Embedded CSS: This can be used when a single HTML document must be styled uniquely. The CSS rule set should be within the HTML file in the head section i.e the CSS is embedded within the HTML file. 

 

External CSS: External CSS contains separate CSS file which contains only style property with the help of tag attributes (For example class, id, heading, … etc). CSS property written in a separate file with .css extension and should be linked to the HTML document using link tag. This means that for each element, style can be set only once and that will be applied across web pages.

                                                      OR

    Explain the different components of multimedia.

Ans:

      The various components of multimedia are Text, Audio, Graphics, Video and Animation. All these components work together to represent information in an effective and easy manner.

1)Text: Text is the most common medium of representing the information. In multimedia, text is mostly use for titles, headlines, menu etc. The most commonly used software for viewing text files are Microsoft Word, Notepad, Word pad etc. Mostly the text files are formatted with, DOC, TXT etc extension.

2)Audio: In multimedia audio means related with recording, playing etc. Audio is an important component of multimedia because this component increase the understandability and improves the clarity of the concept. audio includes speech, music etc. The commonly used software for playing audio files are:

i) Quick Time

ii) Real player
iii) Windows Media Player

3)Graphics: Every multimedia presentation is based on graphics. The used of graphics in multimedia makes the concept more effective and presentable.the commonly used software for viewing graphics are windows Picture, Internet Explorer etc. The commonly used graphics editing software is Adobe Photoshop through which graphics can be edited easily and can be make effective and attractive.

4)Video: Video means moving pictures with sound. It is the best way to communicate with each other. In multimedia it is used to makes the information more presentable and it saves a large amount of time. The commonly used software for viewing videos are:

i) Quick Time

ii) Window Media Player
iii) Real Player

5)Animation: In computer animation is used to make changes to the images so that the sequence of the images appears to be moving pictures. An animated sequence shows a number of frames per second to produce an effect of motion in the user's eye. Some of the commonly used software for viewing animation are:

i) Internet Explorer

ii) Windows Pictures
iii) Fax Viewer

These are the components of Multimedia. Now I am going to talk about its applications.

4. Differentiate between the do and while loop.

   Ans:

         The differentiate between do and while loop are below in table:

	Do-while loop	While loop
1.	In do while loop test condition is evaluated after the loop is executed.	In the while loop the test condition is evaluated before the loop is executed.
2.	It is an exit controlled loop	It is an entry controlled loop
3.	It has two keywords do and while.	It has a keyword while
4.	Loop is terminated with semicolon.	Loop is not terminated with semicolon.

 

5. Suggest the prevention methods of cybercrime.

 Ans:

           The prevention methods of cybercrime are mention in point

1.     Use full services internet security suite

2.     Use strong passwords

3.     Keep your software update.

4.     Manage your social media setting.

5.     Do not download unnecessary software, apk, video, game etc..

6.     Backup data and information regularly to reduce the damage.

7.     Active 2FA on every online account when possible.

8.     Use two-factor authentication (2FA) apps or physical security keys.

9.     Use antivirus software to prevent of hacking, virus etc..

10.                        Be careful while using public WiFi.

   

                                                    Group 'C'

Give long answer to the following question           (2 x 8=16)

6. Explain computer architecture with block diagram and functions of its components.

   Ans:

         The design, arrangement, construction or organization of the different part of the computer is known as architecture. Computer Block Diagram System: Mainly computer system consists of three parts that are central processing unit (CPU), Input Devices, and Output Devices. The Central Processing Unit (CPU) is divided into two parts again: arithmetic logic unit (ALU) and the control unit (CU). The set of instruction is in the form of raw data.

A large amount of data is stored in the computer memory with the help of primary and secondary storage devices. The CPU is like the heart/brain of the computer. The user does not get the desired output, without the necessary option taken by the CPU.  The Central processing unit (CPU) is responsible for the processing of all the instructions which are given by the user to the computer system.

                             

The data is entered through input devices such as the keyboard, mouse, etc. This set of instruction is processed by the CPU after getting the input by the user, and then the computer system produces the output. The computer can show the output with the help of output devices to the user, such as  monitor, printer, etc.

·         CPU (Central Processing Unit)

·         Storage Unit

·         ALU(Arithmetic Logic Unit)

·         Control Unit

 

                                                            OR

   Write a program to input the elements of 4 x 3 matrix and prints its elements properly using array.

 

7. Draw AND, OR, XOR and XNOR gates with truth table and logic gates.

  Ans:

AND:

OR:

XOR:

XNOR:

Malicious Software

Just like the real world, the online world is full of both wonder and danger. For every good thing that jumps out to get your attention, there is also a shady threat lurking in the background, waiting to pounce on their next unsuspecting victim. This might sound a touch melodramatic, but that is the reality.

Everyone knows what a computer virus is, and most people have some understanding of what they can do. However, most people do not understand the broader picture. Viruses are just one form of malware, and so they represent only one small part of the total threat analysis. To try and remedy this problem, let’s go over the basics of malware: What it is, how it works, and how to protect yourself.

What Is Malicious Software?

Malicious software (often called malware for short) is any type of software that is intended to harm or hack the user. They might be attempting to steal your information, or they might simply do it for malicious reasons. Either way, it’s not worth the time to wonder about the motivations of a hacker. Instead, it’s best to focus on questions that you might actually be able to answer.

It’s very hard to pin down a definition for malware because it can work in so many different ways. Anything that is intended to cause harm or gain unauthorized access would fall under this broad heading, and that’s probably all you need to know.

What Can Malicious Software Do To A Computer?

First of all, the risk of malware is by no means limited to the computer. Any device which is capable of connecting to the internet might potentially be infected. Once infected, all sorts of bad things might happen.

For one thing, malware can allow someone else to take control of your computer/device. This might include the installation of programs, the changing of settings or passwords, or the theft of intellectual property (among other things). Anything that you put on the computer will be accessible to the one who controls the malware.

Ransomware Attacks

In many cases, malware is intended to bring about monetary gain for the attacker. In recent years, malware attacks have been used to lock people out of their computer systems. In cases like these, which are called “ransomware attacks,” the attacker will first infect your computer via phishing or some other social-engineering method. Then, they will use the illegitimate access they have gained to encrypt the entire hard drive. Normally, this will be followed up with a ransom demand, and the victim cannot regain access until they do as the hacker demands.

Keyloggers

Obviously, ransomware attacks are seldom carried out against private individuals. Only companies and corporations have enough money to be appealing as ransomware targets. If someone infects your private computer with malware, they will probably have more modest goals. For instance, they can use a special type of malware called a keylogger to capture your online banking login info.

A keylogger is pretty self-explanatory. It spies on your computer and records every keystroke that is made. This will include everything from mundane internet searches to sensitive login credentials.

Password Crackers

Yes, there are programs that can crack your password, but it’s not as bad as it might sound. These programs work by taking hundreds or even thousands of guesses. Obviously, most of those guesses will be wrong, but the computer is able to learn a tiny bit from every failed guess. Eventually, they can construct a complete set of login credentials. The good news is that these programs take a very long time to do their work. Thus, they are virtually useless against long and complex passwords.

APT Malware

In some cases, a hacker might have personal motivations for infecting you with malware. For instance, there have been cases in which people have used malware to spy on former partners or spouses who have rejected them. As petty as this might sound, there are plenty of people out there who are petty enough to do this.

If someone is trying to spy on you, they will probably use something called an APT (advanced persistent threat). This is like the undercover ninja of the malware world. The ninja does not expose himself, nor do anything that might draw attention. Instead, he sits in the background and quietly gathers information, doing nothing that might reveal his presence.

However, this kind of hacking is by no means innocent. Stalkers, serial killers, and other dangerous/deranged individuals can potentially use this sort of software to find and stalk their victims. Here’s a point to remember: Malware is almost always designed to get something from you. If they aren’t after your money or your data, they may be after you.

Trojans

Trojans are basically programs in disguise. They masquerade as a trusted program so that you will open them. Once opened and given permission to install, they act as a vector with which to install all sorts of other disruptive malware. This software is named for a deceptive war tactic that was once used by the Greeks against their Trojan enemies. They pretended to retreat after presenting the trojans with a huge wooden horse, presumably as a peace offering. Little did the Trojans know that the Greeks had hidden their soldiers inside this horse. When the Trojan horse was brought inside the gate, The city of Troy was doomed.

Worms

Worms are some of the worst computer viruses of all. They behave a lot like other types of malware, except for one important difference: These viruses are self-replicating. Once set loose, they act as if they have a mind of their own. Like an infestation of worms, they will continue to reproduce, infecting any new system with which they come into contact.

As an example of how bad these programs can be, we might mention the Code Red virus (A.K.A. The Red Worm), which was first detected in 2001. Although this worm was neutralized fairly quickly upon discovery, it had already infected about 359,000 computers. This one garnered a lot of media attention because some highly confidential government information was hacked and released before the worm was discovered.

How To Guard Against Malicious Software

There are quite a few things you can do to guard against malicious software, and most of these measures are not overly technical. Quite honestly, most people are only vulnerable to malware because they don’t take the threat seriously. With a few simple precautions, you can make yourself a lot harder to hack.

Always Use Strong Passwords

Password cracking programs can be defeated pretty easily. All you have to do is make sure that all your passwords meet the following criteria:

• 18-20 characters long
• Contains a mix of uppercase and lowercase letters
• Contains at least a few numbers
• Contains at least one symbol
• No dictionary words

The best thing you can do here is to make up your own words. If you make up a random nonsense word that has no meaning in any language, it will be virtually impossible for any program to get through.

Be Careful Where You Click

Phishing attacks are a little bit harder, as they rely on tricking the user into giving up their crucial information. The main thing you have to worry about here is clicking on boobytrapped links. What do we mean by that, you ask? Well, it’s very simple. Malware can be embedded in a web link, causing it to be used on anyone who clicks the link. Most “doxing” attacks (i.e., attacks that are aimed at a person’s anonymity) occur in this way. Once you have clicked on that link, the attacker has your IP address, and that info will often be attached to your full name and home address.

Consider The Use Of Digital Disguise

Here’s an innovative idea that you might want to try: Disguise your computer! Here’s the concept: All malware has to be custom-tailored for one type of operating system or another. Some viruses are meant to infect Windows operating systems, while others might be made to target IOS or even Linux. For the record, the vast majority of malware programs are made to target Windows computers. There are two reasons for this. For one, Windows security is an absolute joke, and it’s not the funny kind. Their security is so abysmal that it has become a hacker’s playground. Apple and Linux fare much better in this department, but they are not immune.

Anyway, if you can spoof your Windows system to look like IOS or Fedora or something like that, it will really throw hackers for a loop. If you can fool them into thinking that your Windows computer is running Ubuntu (for example), they will send a virus that is tailored for Linux-based operating systems like that one. However, because this is actually a Windows computer, those attacks will be completely ineffective.

Always Stay Updated

In some ways, cybersecurity is like an arms race. Hackers and other bad actors are constantly looking for new weaknesses to exploit, while cybersecurity professionals are constantly looking for ways to close those loopholes. This is one of the main reasons that your computer (and all of its programs) have to be updated from time to time. Yes, the Windows update process is tedious, but it will help to make your system secure against the latest threats.

The viruses that were effective in the past are no longer effective in the present, and frequent updating is the reason for that. For instance, consider the “red worm” virus that we talked about earlier. Once it was identified, it was quickly neutralized. That happened because the red worm virus was exploiting a bug in certain computer systems. This bug was related to buffer overflow and was only exploitable because no one knew it existed. Because of all the security updates that have taken place since then, the red worm would never work in today’s world.

Conclusion

We should mention that malware is not a simple or easy subject. There are so many vectors of attack that we didn’t even have space to mention all of them. However, you should now have enough knowledge to understand how malware works and how you can guard yourself against it. You don’t have to be a cybersecurity professional to understand a few basic concepts and protect yourself accordingly.