NEB year 2074 computer science questions and solutions

 NEB 2074 computer science questions:

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NEB - Grade-XII 2074(2017) Computer Science
Candidates are requested to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Time: 3 hrs.		Full Marks : 75
		Pass Marks : 27
	Group “A”    [Long Answer questions]		4*10=40
Attempts any Four  questions:
1.	a) What is switch statement in C program? Explain with example. b) Explain FOR loop in C with example.			5 5
2.	Describe the syntax of array. Write a program to sort ten integers numbers in ascending order.			2+8
3.	What are the methods of function declaration and call in C? Write a program to find out given number is odd or even using function.			4+6
4.	What is string? Explain any four string function with examples.			2+8
5.	What is structure in C? Write a program to enter the 20 employee’s name, age and salary using structure and print them.			2+8
	Group “B”    [Short Answer questions]			7*5=35
Attempts any Seven questions:
6.	What are the software development process phases in SDLC? Explain any one phase.			2+3
7.	What are the roles of DBA? Explain.			5
8.	What are 1NF and 2NF normalization principle in Database? Explain.			5
9.	Explain Unshielded Twisted Pair(UTP) cable and Coaxial cable.			2.5+2.5
10.	Differentiate between LAN and WAN.			5
11.	Explain the file handling concept on C.			5
12.	List out the different operator in C. Describe logical operator with example.			2+3
13.	What are advantages and disadvantages of social media? List out.			5
14.	What is cyber crime? How do you affected from cybercrime in your daily life?			2+3
15.	Write short notes on :       a) Data Security                  b) Bluetooth			2.5+2.5

 

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Answers:

NEB - Grade-XII 2074(2017) Computer Science
Candidates are requested to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Time:3 hrs.		Full Marks : 75
		Pass Marks : 27
	Group “A”    [Long Answer questions]		4*10=40
Attempts any Four  questions:
1.	a) What is switch statement in C program? Explain with example. Ans: Switch case statement is a multipath decision making statement that allows selection and execution of a particular block of statements from several blocks of statement based upon the value of expression which is included within the switch statement and branches accordingly. The expression must be of an integral value (“integral” values are simply values that can be expressed as an integer, such as the value of a char). Syntax: switch(expression) { case constant 1:           statement 1; break; case constant 2:         statement 2; break;         case constant n-1: statement n-1; break; default: statement n; } Description:- When the switch statement is executed, the value of expression is compared with the value of case constant (constant1 , constant2...) Then the block of statements associated with the case whose value is matched with expression will be executed. a break statement at the end of block indicates the end of the particular case and cause an exit from switch statement and control will be transferred to statements following with switch. If none of the cases match with the value of the expression, then the block of statement under default is executed. Flowchart: Its flowchart can be represented as: Example: #include <stdio.h> int main() {  char ch; printf("enter choice\n"); scanf("%c",&ch); switch(ch) { case 'b': case 'B': printf("It is second letter"); break; case 'z': case 'Z': printf("It is last letter"); break; default: printf("other letter"); } return 0; } In this program if we enter characters as used in program, it prints related message. Otherwise, it says other letter. It tests the characters in parallel form rather serial.So it is supposed to be faster than if..else if ladder

b) Explain FOR loop in C with example. Ans:- For loop:- Definition:- It is the most common type of loop which is used to execute a program statement or block of program statements repeatedly for a specified number of times. It is a definite loop. Mainly it consists of three expressions: initialization, condition and increment / decrement. The initialization defines the loop starting point, condition defines the loop stopping points and counter helps to increment and decrement the value of counter variable. Syntax of for Loop: for(initialization;condition;increment/decrement ) { statements; } Flowchart:- Example:- #include<stdio.h> int main() { int i; for(i=1;i<=5;i++) {     printf("%d,",i); } return 0; } Output:- It prints 1,2,3,4 and 5			5 5
2.	Describe the syntax of array. Write a program to sort ten integers numbers in ascending order. Ans:Array Definition: A composite variable capable of holding multiple data of same data type under a single variable name is called array. Features: ->stores multiple values ->helps to solve complex porblem ->can be used as array as pointer ->pixel based graphics programming made easier etc Declaration of Array/syntax: datatype array_name [size]; Example: - int marks [10]; int x[4]={1,2,3,4}; Array size is fixed at the time of array declaration. Generally, we use for loop () to assign data or item in memory and also use this loop to extract data from memory location. Types of Array: There are 2 types of array. a) One Dimensional Array (1-D): IT is an array where we use one subscript value.It stores value in row in contigous cells. syntax: data type arra[value/size]; For example: int a[10]; This array stores ten value starting from location zero na dends at 9. b) Two Dimensional Array (2-D):an array where we may use two or more than two subscript values. In this we use matrix concept. syntax: data type arra[row size][column size]; For example: int a[2][2]; It uses two rows and two columns. Values are stored as:   Column zero Column one Row 0 à 1(0,0) 2(0,1) Row 1à 3(1,0) 4(1,1) This array stores total four  values starting from location zero and ends at 1. second part:- /* Write a C program that reads 10  integer numbers and arrange them in ascending order*/ #include <stdio.h> int main() {     float numbers[10];     int i,j,k;     printf("Enter numbers\n");     for(i=0;i<10;i++)     {         scanf("%f",&numbers[i]);     }     for(i=0;i<10;i++)     {         for(j=i+1;j<10;j++)         {             if(numbers[i]>numbers[j])             {                 k=numbers[i];                 numbers[i]=numbers[j];                 numbers[j]=k;             }         }     }     printf("numbers in ascending order are=:\n");     for(i=0;i<10;i++)     {         printf("%f\n",numbers[i]);     }     return 0; }			2+8
3.	What are the methods of function declaration and call in C? Write a program to find out given number is odd or even using function. Ans:- There are four methods to use functions:- 1. FUNCTION WITH NO ARGUMENTS AND NO RETURN VALUES:-This user defined function uses no arguments and returns no value.Let's take an example to understand about this. #include<stdio.h> void sum(); int main() {     sum();     return 0; } void sum() {  printf("sum of two numbers =%d",2+4); } In this we have not passed any arguments and no return value in function prototype and in body part.This is the simpalest way to use function. To call , simply we have to put function name inside the main() function. 2.FUNCTION WITH NO ARGUMENTS AND RETURNING SOME VALUES: This user defined function uses no arguments and returns some value.For this we have to take other data type than void for  function.Let's take an example to understand about this. #include<stdio.h> int sum(); int main() {     printf("sum=%d",sum());     return 0; } int sum() {     int a=4,b=5; int c; c=a+b;  return c; } In this we have not passed any arguments but it is returning some valeu of integer data type.For this we have used int data type in function prototype and in body part.This is the alternative methd to use function. Since the call is  of integer type we have to use printff() with %d specifier to print the value/output. 3.FUNCTION WITH ARGUMENTS AND RETURNING NO VALUES. This user defined function uses some arguments/variables and returns no value.For this we have to take  void data tyep for  function.Let's take an example to understand about this. #include<stdio.h> void sum(int,int); int main() {    sum(3,5);     return 0; } void sum(int a,int b) {  int c; c=a+b; printf("sum=%d",c); } In this we have  passed two arguments a and b and it is  returning no value.For this we have used void data type in function prototype and in body part. when the function is called, we have passed two values 3 and 5 as real arguments. These values are copied to variables a and b and are used inside the body part of function. To print the value/output we simply use function name inside the main(). 4.FUNCTION WITH ARGUMENTS AND RETURN VALUES. This user defined function uses some arguments/variables and returns some value.For this, we have to take  other data type than than void data type for  function.Let's take an example to understand about this. #include<stdio.h> int sum(int,int); int main() {   printf("sum is %d", sum(3,5));     return 0; } int sum(int a,int b) {  int c; c=a+b; return c; } In this we have  passed two arguments a and b and it is  returning an integer value value.For this we have used int data type in function prototype and in body part. when the function is called, we have passed two values 3 and 5 as real arguments. These values are copied to variables a and b and are used inside the body part of function. To print the value/output we simply use function name with specifier %d with printf() function inside the main(). SEcond part: /* program to know a number is even or odd using function*/ #include<stdio.h> void even_odd(); int main() {     even_odd();     return 0; } void even_odd() {   int n;   printf("enter a number\n");   scanf("%d",&n);   if(n%2==0)   {          printf("%d is an even number",n);   }  else  {                  printf("%d is an odd number",n); } }			4+6
4.	What is string? Explain any four string function with examples. Ans:- String--            It means series of characters used in our program. We can also use digits with characters. They also act as string or a part of it. It is used when we input our name or address or somewhere their combination. Syntax char identifier[value]; or char identifier[value][value]; We can use he upper one if we want to input single string then. And if we want to input multiple values then we use lower one(called 2-dimensional array in string). For example, char name[100]; gets(name) Here, the variable accepts value having maximum characters 100. We can also write , char name[10]="kathmandu"; IT stores the value in following way. It stores values from cell location '0' and ends at null character called escape sequence. This is used to show that there is no more character beyond that. This null character is used with strings only. For  numbers, it is not used.                         Similarly, if we want to store multiple string with same name then one-dimensional is not applicable. We use two dimensional string. We declare: char name[5][50]; It means, we are going to store any five names having optimum 50 characters. Let's look below. If we have five names :RAM,SHYAM,Nita then it would like so sequentially it stores data in different row. We use loop to execute it with different data. Or, instead of inputting string, if we initialize strings then it can be written as   char name[5][50]={"RAM","Shyam","Nitu"}; second part:- 1) strlen(string);-It is used to get length of given string.  syntax: identifer=strlen(string); For example, #include<stdio.h> #include<string.h> void main() { char string[100]="apple"; int k; k=strlen(string); printf("length=%d",k); } It returns 5. It also counts white spaces present in a string. If we want want , we can also input string using scanf() or gets(). 2)strrev():- It reverses the string given by us. syntax:- strrev(string); example: #include<stdio.h> #include<string.h> void main() { char string[100]="apple"; printf("reverseed string=%s",strrev(string)); } We get output "elppa". Instead of putting in output line, we can put it before printf. 3)strlwr(): This function is used to convert given string into lower case. syntax:- strlwr(string); Example; #include<stdio.h> #include<string.h> void main() { char string[100]="APPLE"; printf("string in lowercase=%s",strlwr(string)); } It gives us "apple" as an  output. 4)strupr():This string function is used to convert all characters of  string into upper case. syntax: strupr(string); example:- #include<stdio.h> #include<string.h> void main() { char string[100]="apple"; printf("string in uppercase=%s",strupr(string)); } We get APPLE as an output after execution.			2+8
5.	What is structure in C? Write a program to enter the 20 employee’s name, age and salary using structure and print them. Ans:- It stores dis-similar data.Each gets separate space in memory.They do not share memory.we can access member in any sequence.It uses keyword 'struct'.We can initialize values of member/s and in any order.It consumes more memory. Its syntax is,     struct tag { datatype member1; datatype member2; datatype member3; }variable; Example struct student { int roll; char sex; float percentage; }var; second part:- /*to input 20 employee's name,age  and salary using struct and print them */ #include <stdio.h> struct emp {     char name[100];     int age;     int salary; }var[20]; int main() {     int i;     printf("enter name,age and salary\n");     for(i=0;i<=19;i++)     {         scanf("%s",var[i].name);         scanf("%d",var[i].age);         scanf("%d",var[i].salary);     }     printf(" name,age and salary of employees are:\n");     for(i=0;i<=19;i++)     {         printf("name=%s,age=%d and salary=%d\n",var[i].name,var[i].age,var[i].salary);              }     return 0; }			2+8
	Group “B”    [Short Answer questions]			7*5=35
Attempts any Seven questions:
6.	What are the software development process phases in SDLC? Explain any one phase. Ans: SDLC is a structure or a process to develop a software followed by a development team within the software organization. It consists of a detailed plan describing how to develop, maintain and replace specific software. SDLC is also known as information systems development or application development. It is life cycle defining a methodology for improving the quality of software and the overall development process.  SDLC's different phases are shown around the circle. 1.Planning/requirements study 2.System ananlysis 3.System design 4.System Development  5.System testing 6.System implementation 7.System evaluation 8System maintenance Planning:- The first step is problem definition(study). The intent is to identify the problem, determine its cause, and outline a strategy for solving it. It defines what ,when who and how project will be carried out.                      As we know everything starts with a concept. It could be a concept of someone, or everyone. However, there are those that do not start out with a concept but with a question, “What do you want?” and "really, is there a problem?" They ask thousands of people in a certain community or age group to know what they want and decide to create an answer. But it all goes back to planning and conceptualization.                                                  In this phase the user identifies the need for a new or changes in old or an improved system in large organizations. This identification may be a part of system planning process. Information requirements of the organization as a whole are examined, and projects to meet these requirements are proactively identified.                                               We can apply techniques like: 1) Collecting data by about system by measuring things, counting things, survey or interview with workers, management, customers, and corporate partners to discover what these people know. 2) observing the processes in action to see where problems lie and improvements can be made in workflow. 3)Research similar systems elsewhere to see how similar problems have been addressed, test the existing system, study the workers in the organization and list the types of information the system needs to produce. 2) Getting the idea about context of problem 3) The processes - you need to know how data is transformed into information.                      Like data structures, storage, constraints that must be put on the solution (e.g. operating system that is used, hardware power, minimum speed required etc,  what strategy will be best to manage the solution etc.			2+3
7.	What are the roles of DBA? Explain. Ans:- Database Administrator:- A database administrator (DBA) is a person/s who is/are responsible for the environmental aspects/activities related to database. The role of a database administrator has changed according to the technology of database management systems (DBMSs) as well as the needs of the owners of the databases.                 Duties/roles: 1. Installation of new software. 2. Configuration of hardware and software with the system administrator 3. Security administration 4. Data analysis 5. Database design (preliminary 6. Data modeling and optimization 7. Responsible for the administration of existing enterprise databases and the analysis, design, and creation of new databases			5
8.	What are 1NF and 2NF normalization principle in Database? Explain. Ans:- Normalization:- In the field of relational database design, normalization is a systematic way of ensuring that a database structure is suitable for general-purpose querying and free of certain undesirable characteristics—insertion, update, and deletion anomalies that could lead to a loss of integrity. 1 NF:          A TABLE IS SAID TO BE IN 1n IF there is not repeating groups or information in a table..Here, repeating group means a set of columns that stores similar information that repeats in the same table. Let’s consider following SQL commands. Create table contacts ( Contact Id               Integer                    not null, L_name                  varchar(20)            not null, F_name                  varchar(20)            Contact_date1      date, Contact_desc1      varchar(50), Contact_date2      date, Contact_desc2      varchar(50), ); We can see here in this table that there is a repeating group of date and description. Now to convert into 1 N, we have to make a new table and shift that repeating group into new table. Like, Create table contacts ( Contact_ID integer        not null, L_name      varchar(20) not null, F_name      varchar(20) );   Create table conversation ( Contact_id integer        not null, Contact_date date, Contact_desc        varchar(50) ); 2N: A table is said to be in 2 N if it is in 1N and there is no redundant data in table i.e. if a value of column is dependent on one column(primary key only) but not another. For example: Create table employee ( Emp_no     integer        not null, L-name       varchar(20) not null, F_name      varchar(20), Dept_code integer, Description varchar(50), ); This table contains redundant data i.e. the value of column(field) “description” depends on dept_code but does not depend on primary key “emp_no”.So let’s make a new table and shift them into that. Create table employee ( Emp_no     integer        not null, L_name      varchar(20) not null, F_name      varchar(20), Dept_code integer, );   Create table department ( Dept_code integer        not null, Description varchar(50) not null, ); We got two tables named employee and department with fields. Both the tables are related by primary key called dept_code. Now there is no redundancy and table is in 2N.			5
9.	Explain Unshielded Twisted Pair(UTP) cable and Coaxial cable. Ans:- UTP:- Unshielded Twisted pair cabling is a type of wiring in which two conductors (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs. Different pairs(colour) have different function.It has 4-pairs of copper wires. UTP cable is also the most common cable used in computer networking. Modern Ethernet, the most common data networking standard, utilizes UTP cables. Twisted pair cabling is often used in data networks for short and medium length connections because of its relatively lower costs compared to optical fiber and coaxial cable. It has bandwidth up to 100mbps but can be increased up to 10000 mbps. The rate at which signal moves is ⅔ of velocity of light. It is available in different categories like CAT5,CAT6 ,CAT7 etc Coaxial cable, or coax, It is an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable is used as a transmission line for radio frequency signals, in applications such as connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals and uses many connectors. It is available in two types thin (10base2; means 100 MBPS and upto 200 meter) and thick (10base5 coax;means 10 MBPS, and upto 5oo meter). They are different in diameter and bandwidth. Most of television operators use this. They are obsolete and no longer in use for computer networking figure :coaxial cable			2.5+2.5
10.	Differentiate between LAN and WAN. Ans:-We can understand about LAN and WAN with the help of  following points. LAN: -  It is a privately-owned network done in single building or room or office to share resources or data, documents (for 100 m).  It occupies small area and small number of computers. Speed with which data is passed is extremely fast(1000mbps). Fast connecting and sharing. Uses medium like Co-axial or utp cable (mostly). can use topology like bus/star/tree etc. fewer error occurrences during transmission. Less congestion can be handled by single person/administrator.  It is cost effect WAN:- is a telecommunications network, usually used for connecting computers, that spans a wide geographical area. WANs can by used to connect cities, states, or even countries.  It occupies broad area(>=50km). Extremely slow transfer rate(150mbps) Slow connecting and file sharing. Mostly uses medium like ,telephone line,leased line or satellite or optical fiber Uses MESH topology. more transmission error high congestion. due to having of complex system, it is handled by a group. Expensive to set-up.			5
11.	Explain the file handling concept on C. Ans:- A file pointer is used to identify a file for any file operations. If you didn’t have a file pointer then the operations to read, write, or even close a file wouldn’t know what file to close. The Operating System doesn’t keep track of filenames, pointers and such, at least not in any way that one can access a filename given a file pointer. That is for the program/programmer of which to keep track. So when a file is opened, a file pointer is returned (at least in C - in C++ that stuff is kept hidden behind the scenes). You use that file pointer for any operations on files after that point so the operation knows on which file to perform its operation. And all a file pointer is a number. · To demonstrate this notice that in C, we have to manually put the * in - FILE *fp; · it’s not there by default so FILE is just a structure and the FILE * is a pointer to that structure in memory. · In languages like Basic and PHP and even assembly language, the file pointer is just literally a number to an open file. Example of file pointer:- In this example we are going to store data using file handling concept. /* Write a program to store name, department and age to file names “employee.dat” .*/ #include<stdio.h> int main() { FILE *fp; char name[30],dept[30]; int age; fp=fopen("employee.dat","a"); printf("Enter name, dept and age of employee"); scanf("%s%s%d",name,dept,&age); fprintf(fp,"\n %s\t %s\t %d",name,dept,age); return 0; }			5
12.	List out the different operator in C. Describe logical operator with example. Ans: Following are some important operators used in C. 1.Arithmetic operator 2.Relational oeprator 3.Logical operator 4.Assignment operator 5.Unary operator 6.sizeof() operator 7.bitwise operator etc. Let's understand about logical operator:-                                     This operator is quite helpful when we want to combine multiple  conditions and take decision.It returns values in the form of 0 o 1.It works logically. Its types are: 3.a)and (&&)-----------> It is called 'and'operator.It is used to combine multiple conditions.It gives us true output if all of them are true otherwise we get false output.  example:if(a>b && a>c)                       {                             display a                              }  we can see here that to be greatest,value of 'a' must be greater than b and c. So we use here '&&'       3.b)or(||):- It is called 'or'operator.It is used to combine multiple conditions.It gives us true output if anyone of them is true or all are true otherwise we get false output.  example:if(a==90 || b==90 || c==90)                       {                             display right angle triangle                           }  we can see here that to be right angled triangle,either 'a'or 'b'or 'c' a must be 90 . So we use here '||'. 3.c) !(not )operator:-                                 It is used to reverse the result. example int a=5; if(!(a==5)) { printf("it is\n"); } else { printf("it is not\n"); } here ,the value is 5 but we get output "it is not".It is called reversing the output.			2+3
13.	What are advantages and disadvantages of social media? List out. Ans:- Social media can be a useful tool for businesses, bringing advantages such as engaging with your audience and boosting website traffic. However there can also be disadvantages, including the resources required and negative feedback. Considering these pros and cons can help you decide the best approach to social media for your business. Advantages of social media The business benefits of effective social media use include: Brand awareness - Compelling and relevant content will grab the attention of potential customers and increase brand visibility.  Brand reputation - We can respond instantly to industry developments and be seen as 'thought leader' or expert in your field. This can improve how our business is seen by your audience.  Cost effective - It can be much cheaper than traditional advertising and promotional activities. The costs of maintaining a social media presence are minimal. If you choose to invest in paid advertising, We can spend as much or as little as your budget allows. Disadvantages of social media Some of the downsides of using social media include: Resources - You will need to commit resources to managing your social media presence, responding to feedback and producing new content. This can include hiring and training staff, investing in paid advertising and paying for the costs of creating video or image content. Evaluation - While it is easy to quantify the return-on-investment in terms of online sales generated by social media advertising - there are some less tangible benefits. It can be hard to measure and place a monetary value on the brand awareness and reputation that social media can bring. It's difficult to know how social media effects sales in-store. Ineffective use - Social media can be used ineffectively. For example, using social media to push for sales without engaging with customers, or failing to respond to negative feedback - may damage your reputation.			5
14.	What is cyber crime? How do you affected from cybercrime in your daily life? Ans:- Cyber crime:- Alternatively referred to as cyber crime, e-crime, electronic crime, or hi-tech crime. Computer crime is an act performed by a knowledgeable computer user, sometimes referred to as a hacker that illegally browses or steals a company's or individual's private information. In some cases, this person or group of individuals may be malicious and destroy or otherwise corrupt the computer or data files. Below is a listing of the different types of computer crimes today. Clicking on any of the links below gives further information about each crime. Different types of crime using this we can get affected:- 1.Pornogrphy 2.Hacking 3.DOS 4.Phising etc Protection method: 1. Use a full-service internet security suite 2. Use strong passwords 3. Keep your software updated 4. Manage your social media settings 5.Talk to your children about the internet 6. Keep up to date on major security breaches			2+3
15.	Write short notes on :       a) Data Security                  b) Bluetooth Ans: a)Data security:-  It simply says protection of data /information contained in database against unauthorized access, modification or destruction. The main condition for database security is to have “database integrity’ which says about mechanism to keep data in consistent form. Besides these all, we can apply different level of securities like: Physical: - It says about sites where data is stored must be physically secured. Human: - It is an authorization is given to user to reduce chance of any information leakage or manipulation. Operating system: We must take a foolproof operating system regarding security such that no weakness in o.s. Network: - since database is shared in network so the software level security for database must be maintained. Database system: - the data in database needs final level of access control i.e. a user only should be allowed to read and issue queries but not should be allowed to modify data			2.5+2.5

    b)Bluetooth:-

               Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances using UHF radio waves in the ISM bands, from 2.402 GHz to 2.48 GHz, and building personal area networks (PANs). It was originally conceived as a wireless alternative to RS-232 data cables. It is mainly used as an alternative to wire connections, to exchange files between nearby portable devices and connect cell phones and music players with wireless headphones. In the most widely used mode, transmission power is limited to 2.5 milliwatts, giving it a very short range of up to 10 meters (30 feet).

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source:-

->nibusinessinfo.co.uk

->wikipedia.org

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