Category: CBSE Sample Papers

Students can access the CBSE Sample Papers for Class 12 Computer Science with Solutions and marking scheme Term 2 Set 6 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Computer Science Term 2 Set 6 for Practice

Time: 2 Hours
Maximum Marks: 35

General Instructions:

• The question paper is divided into 3 sections – A, B and C
• Section A, consists of 7 questions (1 – 7). Each question carries 2 marks.
• Section B, consists of 3 questions (8 – 10). Each question carries 3 marks.
• Section C, consists of 3 questions (11 – 13). Each question carries 4 marks.
• Internal choices have been given for question numbers 7, 8 and 12.

Section – A
(2 Marks Each)

Question 1.
Convert to postfix notation:
(A+B)*C/D

Question 2.
(a) Expand the following:
PPP, HTML

(b) Rahul has to share the data among various computers of his two office branches situated in the same city. Name the network (out of LAN, MAN,PAN and MAN) which is being formed in this process.

Question 3.
Explain database.

Question 4.
Consider the statement given below:
MySQLdb.connect(‘localhost’,’LibMan’,’isspwd’,’Library’)

(a) What is “Library” in the statement?

(b) What is “LibMan” in the statement?

Question 5.
Write the output of the queries (a) to (d) based on table, SPORTS given below:
Table: SPORTS

ADMNO	GAME	COACHNAME	GRADE
1215	CRICKET	MR RAVI	A
1213	VOLLEYBALL	MR. AMANDEEP	B
1211	VOLLEYBALL	MR. GOVARDHAN	A
1212	BASKETBALL	MR. TEWARI	B

(a) SELECT GAME FROM SPORTS WHERE GRADE=’A’;

(b) SELECT COACHNAME FROM SPORTS WHERE GAME LIKE ‘%KET’;

(c) SELECT ADMNO, GRADE FROM SPROTS WHERE ADMNO>1215;

(d) SELECT GRADE FROM SPORTS WHERE GAME=”BASKETBALL;

Question 6.
(a) Which command is used to modify the records of the table?

(b) What is a query result set?

Question 7.
Consider the table Patients:
Table: Patients

PatNO	PatName	Dept	DocID
1	Leena	ENT	100
2	Supreeth	Ortho	200
3	Madhu	ENT	100
4	Neha	ENT	100
5	Deepak	Ortho	200

(a) What is degree?

(b) Define cardinality.

OR

(a) Identify the degree and cardinality of table Patients.

(b) Identify the primary key of table Patients.

Section – B
(3 Marks Each)

Question 8.
Write a function to push any student’s information to stack.
OR
Convert (A+ (B*C – (D/ E ^ F) * G) * H) into postfix form showing stack status after every step.

Question 9.
(a) Which type of relationship is supported by network model?

(b) What is join in SQL?

Question 10.
Create following table using Python code.
Table Name = Customer
Database – xyzcorp Userid – Adminxyz Password – Axydml2

CUSTNUMB	CUSTNAME	ADDRESS	BALANCE	CREDLIM	SLSRNUMB
124	TINA ADAMS	481 Tilak lane, CP, Delhi	41800.75	50,000	3
256	R VENKAT	215 Mylapore, Chennai	100000.75	80,000	6
567	BHUVNA BALAJI	808,  Bala  Nagar, Hyderabad	57,000.75	50000	6
622	PRATHAMJAIN	149, Plot 182, sec-9 Dwarka, Delhi	57500.75	80,000	12

Section – C
(4 Marks Each)

Question 11.
Write SQL queries for (a) to (d) based on tables, ACCOUNT and TRANSACT given below:
TABLE: ACCOUNT

ANO	ANAME	ADDRESS
101	Nirja Singh	Bangalore
102	Rohan Gupta	Chennai
103	Ali Reza	Hyderabad
104	Rishabh Jain	Chennai
105	Simran Kaur	Chandigarh

TABLE: TRANSACT

TRNO	ANO	AMOUNT	TYPE	DOT
T001	101	2500	Withdraw	2017-12-21
T002	103	3000	Deposit	2017 – 06 -1
T003	102	2000	Withdraw	2017-06-12
T004	103	1000	Deposit	2017-10-22
T005	101	12000	Deposit	2017-11-06

(a) To display details of all transactions of TYPE Deposit from Table TRANSACT.

(b) To display the ANO and AMOUNT of all Deposits and Withdrawals done in the month of October 2017 from table TRANSACT

(c) To display the last date of transaction (DOT) from the table TRANSACT for the Accounts having ANO as 103.

(d) To display the ANAME and AMOUNT from tables given above for those whose address is Chennai.

Question 12.
(a) Write one advantage of bus topology of network. Also illustrate how four (4) computers can be
connected with each other using bus topology of network.
OR
Explain the purpose of a Switch.

(b) What is the difference between e-mail and chat?

Question 13.
Meerut school in Meerut is starting up the network between its different wings. There are four buildings named as S, J, A and H.
The distance between various buildings is as follows:

A to S	200 m
A to J	150 m
AtoH	50 m
S to J	250 m
StoH	350 m
J to H	350 m

Number of computers in each Building:

S	130
J	80
A	160
H	50

(a) Suggest the cable layout of connections between the buildings.

(b) Suggest the most suitable place (i.e. building) to house the server of this school, provide a suitable reason.

(c) Suggest the placement of the following devices with justification:

• Repeater
• Hub/Switch

(d) The organization also has inquiry office in another city about 50-60 km away in hilly region. Suggest the suitable transmission media to interconnect to school and inquiry office out of the following:

• Fibre optic cable
• Micro wave
• Radio wave

Students can access the CBSE Sample Papers for Class 12 Computer Science with Solutions and marking scheme Term 2 Set 3 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Computer Science Term 2 Set 3 with Solutions

Time: 2 Hours
Maximum Marks: 35

General Instructions:

• The question paper is divided into 3 sections – A, B and C
• Section A, consists of 7 questions (1 – 7). Each question carries 2 marks.
• Section B, consists of 3 questions (8 – 10). Each question carries 3 marks.
• Section C, consists of 3 questions (11 – 13). Each question carries 4 marks.
• Internal choices have been given for question numbers 7, 8 and 12.

Section – A
(2 Marks Each)

Question 1.
Give few applications of stack.
Answer:

• Expression evaluation.
• Backtracking (game playing, finding paths,exhaustive searching).
• Memory management, run-time environment for nested language features.

Question 2.
(a) Expand the following Oil
HTTP, TCP
Answer:

• HTTP – Hyper Text Transfer Protocol.
• TCP – Transmission Control Protocol.

(b) Which protocol is used in creating a connection with a remote machine? HD
Answer:
Telnet is a protocol that is used in creating a connection with a remote machine.

Question 3.
What is relation? Define the Relational Data Model.
Answer:

• A relation is a table having atomic values, unique and unordered rows and columns.
• The relational model represents data and relationship among data by a collection of tables known as relation, each of which has a number of columns with unique names.

Question 4.
An output is extracted from the database using the cursor object by giving the following statement. Mycon = cursor.fetchmany(size)
(a) How many records will be returned by fetchmany(size) method?
Answer:
It returns the number of records specified by the size argument.

(b) What will be the datatype of Mycon object after the given command is executed?
Answer:
list

Question 5.
Write the output of the queries (a) to (d) on the table, SCHOOL given below:
Table: SCHOOL

CODE	TEACHER	SUBJECT	DOJ	PERIODS	EXPERIENCE
1001	RAVI SHANKAR	ENGLISH	12/3/2000	24	10
1009	PRIYA RAI	PHYSICS	03/09/1998	26	12
1203	LIS ANAND	ENGLISH	90/04/2000	27	5
1045	YASHRAJ	MATHS	28/8/2000	24	15
1123	GAGAN	PHYSICS	16/7/1999	28	3
1167	1 lansh B	Chemistry	19/10/1999	27	5
1215	Umesh	Physics	11/05/1998	i 22	16

(a) SELECT MAX (EXPERIENCE) FROM SCHOOL;
Answer:
16

(b) SELECT TEACHER FROM SCHOOL WHERE EXPERIENCE >12 ORDER BY TEACHER;
Answer:
UMESH YASHRAJ

(c) SELECT SUM (PERIODS) FROM SCHOOL WHERE SUBJECT LIKE “E%”;
Answer:
51

(d) SELECT SUBJECT FROM SCHOOL WHERE PERIODS <25 AND EXPERIENCE > 15;
Answer:
PYHISCS

Question 6.
(a) Which keyword is used to sort the records of a table in descending order?
Answer:
DESC

(b) What is a database connection?
Answer:
A database connection is a mean to communicate form of the script to a database program.

Question 7.
Consider the table, CUSTOMER given below:
Table: CUSTOMER

CNO	CNAME	Address
101	Richa Jain	Delhi
102	Surbhi Sinha	Chennai
103	Lisa Thomas	Bangalore
104	Imran Ali	Delhi
105	Roshan Singh	Chennai

(a) Identify the degree and cardinality of given table
Answer:

• Degree : 3
• Cardinality : 5

(b) Which field should be made the primary key?
Answer:
CNO

OR
(a) Identify the candidate key(s) from the table CUSTOMER.
Answer:
CNO, CNAME

(b) Which command is used to add new column into table CUSTOMER?
Answer:
ALTER TABLE

Section – B
(3 Marks Each)

Question 8.
Write a program to print a string in reverse order, using stack.
OR
Evaluate the following Postfix expression : 20,10, -, 15, 3, /, +, 5, *
Answer:
def pushstack(stack,ch):
stack.append(ch) top=len(stack)-1 return
def popstack(stack):
if isempty(stack):
else:
top=len(stack)-1 ”
for a in range(top, -1, -1): print (stack[a]) return
def is empty(stack): if stack== [ ]:
return True
else:
return False
Commonly Made Error:
Students use keywords or similar name for identifiers which show error.

Answering Tip:
Try to use meaningful name identifiers and do not use keywords or similar name for identifiers.

OR

Symbol	Operation	:    Stack …	Result
20	Push	20
10	Push	20, 10
	Pop (10) Pop (20) Push (20 – 10) = 10	10
15	Push	10, 15
3	Push	10, 15, 3
/	Pop (3) Pop (15) Push (15/3)=5	10, 5
+	Pop (5) Pop (10) Push (10+5) = 15	15
5	Push	15, 5
★	Pop (5) Pop (15)	75
	Push (15*5)=75	:    Stack …

Result : 75

Question 9.
(a) In SQL, write the query to display the list of tables stored in a database.
Answer:
SHOW TABLES;

(b) Sonal needs to display name of teachers, who have “O” as the third character in their name. She wrote the following query.
SELECT NAME FROM TEACHER WHERE NAME = “**0?”;
Answer:
The wildcards are incorrect. The corrected query is SELECT NAME FROM TEACHER WHERE NAME LIKE ‘- -0%’;

Question 10.
(a) Sahil has to create a database named KNOWLEDGE in MYSQL.
He now needs to create a table named STUDENT in the database to store the records. The table STUDENT has the following structure:

FIELD NAME	DATATYPE	REMARKS
ADMNO	INTEGER CHAR(20) INTEGER CHAR(2) INTEGER VARCHAR (30)	Primary Key Not Null
NAME	DATATYPE
CLASS	INTEGER CHAR(20) INTEGER CHAR(2) INTEGER VARCHAR (30)
SEC	DATATYPE
RNO	INTEGER CHAR(20) INTEGER CHAR(2) INTEGER VARCHAR (30)
ADRESS	DATATYPE

Help him to complete the task by suggesting appropriate SQL commands.
Answer:
CREATE DATABASE KNOWLEDGE;
CREATE TABLE STUDENT(
ADMNO INT PRIMARY KEY,
NAME CHAR(20) NOT NULL,
CLASS INT,
SEC CHAR(2),
RNO INT,
ADDRESS VARCHAR(30)
) ;

Section – C
( 4 Marks Each)

Question 11.
Write SQL queries for (a) to (b) based on the given tables, CUSTOMER and TRANSACTION.
Table: CUSTOMER

CNO	CNAME	ADRESS
101	Richa Jain	Delhi
102	Surbhi Sinha
103	Lisha Thomas	Bangalore
104	Imran Ali	Delhi
105	Roshan Singh	Chennai

Table: TRANSACTION

TNO	CNO	Amount	TYPE	DOT
T001	101	1500	Credit	2007-11-23
T002	103	2000	Debit	2007-05-12
T003	102	3000	Credit	2007-06-10
T004	103	12000	Credit	2007-09-12
T005	102	1000	Debit	2007-09-05

(a) To display the detail of customers whose include Ali in their name.
Answer:
SELECT * FROM CUSTOMER WHERE CNAME LIKE “%ALi”;

(b) To display the AMOUNT of all Transactions done in the 2017 from table TRANSACTION.
Answer:
SELECT AMOUNT FROM TRANSACTION WHERE DOT = 2017);

(c) To display the last date of transaction (DOT) from the table TRANSACTION for the customer having CNO as 103.
Answer:
SELECT MAX (DOT) FROM TRANSACTION WHERE CNO=”103″;

(d) To display CNO, CNAME and TYPE with the help of both tables where address is not in Delhi and Bangalore-
Answer:
SELECT CNO, CNAME, TYPE FROM CUSTOMER C, TRANSACTION T WHERE C.CNO=T. CNO AND ADDRESS NOT IN (‘DELHI’, ‘BANGALORE’);

Question 12. (i) What do you mean by a modem? Why is it used?
OR
Identify the type of topology from the following:
(a) Each node can have an arbitrary number of child nodes.
Answer:
A MODEM (Modulator Demodulator) is an electronic device that enables a computer to transmit data over telephone lines. It converts the digital signals, governed by the source computer into analog form for transmission over the telephone lines. At the receiving end it converts received analog signal into digital signals.
Tree topology.

(b) Each node is connected with hub through independent cables.
Answer:
Star topology.

(ii) Write any two differences between twisted pair cable and coaxial cable.
Answer:

Twisted pair cable	Co-axial cable
(i) Their bandwidth is not as high as coaxial cables.	(i) It has high bandwidth.
(ii) A twisted pair consists of two copper wires twisted around each other (each has its own insulation around it) like a double helix.	(ii) A coaxial cable consists of a copper wire core covered by an insulating material and a layer of conducting material over that.

Question 13.
ABC Pvt. Ltd. is setting up the network in the Bengaluru. There are four departments named as Market, Finance, Legal and Sales.
Distance between various building follows:

Market to Finance	80 mt
Market to legal	180 mt
Market to Sales	100 mt
Legal to Sales	150 mt
Finance to Sales	50 mt

Number of computer in building:

Market	20
Legal	10
Finance	08
Sales	42

(a) Suggest a cable layout of connections between the Departments and specify the topology.
Answer:

Star topology should be used.

(b) Suggest the most suitable building to place the server by giving suitable reason.
Answer:
Sales is the most suitable building to place the server because it has maximum no. of computers.

(c) Suggest the placement of (i) Modem (ii) Hub/Switch in the network.
Answer:
Each building should have Hub/Switch and Modem in case Internal connection is required

(d) The organization is planning to link its sale counter situated in various part of the same city. Which type of network out of LAN, WAN, MAN will be formed? Justify.
Answer:
MAN (Metropolitan Area Network).

Students can access the CBSE Sample Papers for Class 12 Computer Science with Solutions and marking scheme Term 2 Set 5 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Computer Science Term 2 Set 5 with Solutions

Time: 2 Hours
Maximum Marks: 35

General Instructions:

• The question paper is divided into 3 sections – A, B and C
• Section A, consists of 7 questions (1 – 7). Each question carries 2 marks.
• Section B, consists of 3 questions (8 – 10). Each question carries 3 marks.
• Section C, consists of 3 questions (11 – 13). Each question carries 4 marks.
• Internal choices have been given for question numbers 7, 8 and 12.

Section – A
(2 Marks Each)

Question 1.
Define stack.
Answer:
A stack is a data structure that allows addition and removal of elements in a particular order. Every time; an element is added, it goes on the top of the stack and the only element that can be removed is the element that was at the top of the stack.

Question 2.
(i) Expand the following
FTP, VoIP
Answer:

• FTP – file Transfer Protocol.
• VoIP – Voice over Internet Protocol.

(ii) Which type of network out of LAN, PAN and MAN is formed, when you connect two mobiles using Bluetooth to transfer a video?
Answer:
PAN (Personal Area Network).

Question 3.
What is table? Also, define Candidate Key. BD
Answer:
A table consists of a number of rows and columns. Each record contains values for the attributes. A candidate key is the smallest subset of the super key for which there does not exist a proper subset; that is super key. In other words, all attribute combinations inside a relation that can serve as primary key are candidate keys.

Question 4.
Consider the following statement and answer the following questions cursor, rowcount
(a) What is row count ?
Answer:
The rowcount is a property of cursor object that returns the number of rows retrieved from the; cursor so far.

(b) Where is row count used ?
Answer:
rowcount is used frequently in the loops to prevent the infinite loops.

Question 5.
Write output for SQL queries (a) to (d), which are based on the table: STUDENT given below:
Table: STUDENT

ItemNo	Item	Scode	Qty	Rate	LastBuy
2005	Sharpener Classic	23	60	8	31-Jun-09
2003	Ball Pen 0.25	22	50	25	01-Feb-10
2002	Gel Pen Premimum	21	150	12	24-Feb-10
2006	Gel Pen Classic	21	250	20	11-Mar-09
2001	Eraser Small	22	220	6	19-Jun-09
2004	Eraser Big	22	110	8	02-Dec-09
2009	Ball Pen 0.5	21	180	18	03-Nov-09

(a) SELECT COUNT(DISTINCT Scode) FROM STORE;
Answer:
COUNT(DISTINCT Scode)
3

(b) SELECT Rate* Qty FROM STORE WHERE ItemNo=2004;
Answer:
Rate* Qty
880

(c) SELECT MAX(Qty) FROM STORE;
Answer:
AX(Qty) s
250

(d) SELECT SUM(Rate) FROM STORE WHERE Scode=22;
Answer:
SUM(Rate):
39

Question 6.
(a) What is primary key?
Answer:
A primary key is a set of one or more attributes that can uniquely identify the relation.

(b) What is My SQLdb?
Answer:
MySQLdb is an interface for connecting to a MySQL database server from Python.

Question 7.
Observe the following table Pro_Info carefully:

PID	PNAME	QTY	PRICE	COMPANY	SUPCODE
101	DEGITAL CAMERA 14X	120	12,000	RENBIX	SOI
102	DIGITAL PAD lli	100	22,000	DIGI POP	S02
104	Stapler Medium	500	1,100	STOREKING	SOI
106	Punching Machine Big	70	28,000	DISPEXPERTS	S02
105	Stapler Mini	60	12,000	MOVEON	S03

(a) Identify the primary key of above table.
Answer:
PID

(b) Identify the candidate key(s) of above table.
Answer:
PID, PNAME

OR

(c) Identify the degree and cardinality of table PRODUCT.
Answer:
Degree: 6

(d) Which command is used to remove the tuples from the table?
Answer:
DELETE

Section – B
[3 Marks Each]

Question 8.
Write a python program to demonstrate implementation of stack using lists with proper documentation.
OR
Write an algorithm to convert infix to postfix.
Answer:
# Python program to
# demonstrate stack implementation
# using list stack = []
# append ( ) function to push
# element in the stack
stack, append (‘a’) stack, append (‘d’) stack, append (‘c’) print (‘Initial stack’) print (stack)
# pop ( ) function to pop
# element from stack in
# LIFO order
print (‘\ nElements popped from stack : ‘) print (stack . pop ( ))
print (stack . pop ( ) )
print (stack . pop ( ))
print (‘\nStack after elements are popped :’) print (stack)
# uncommenting print (stack, pop ( ))
# will cause an IndexError
# as the stack is now empty

OR

1. Scan the infix expression from left to right.
2. If the scanned character is an operand, output it.
3. Else,
(i) If the precedence of the scanned operator is greater than the precedence of the operator in the stack (or the stack is empty or the stack contains a ‘(‘), push it.

(ii) Else, Pop all the operators from the stack which are greater than or equal to in precedence than that of the scanned operator. After doing that Push the scanned operator to the stack. (If you encounter parenthesis while popping then stop there and push the scanned operator in the stack.)

(iii) Else, Pop all the operators from the stack which are greater than or equal to in precedence than that of the scanned operator. After doing that Push the scanned operator to the stack. (If you encounter parenthesis while popping then stop there and push the scanned operator in the stack.)

4. If the scanned character is an'(‘, push it to the stack.
5. If the scanned character is an’)’, pop the stack and output it until a'(‘ is encountered, and discard both the parenthesis.
6. Repeat steps 2-6 until infix expression is scanned.
7. Print the output
8. Pop and output from the stack until it is not empty.

Question 9.
(a) Which clause is used to sort the records of a table?
Answer:
ORDER BY

(b) What is the SQL ?
Answer:
SQL refers to structured Query Language, a standard query language used by RDBMs to create, maintain and guery upon their databases.

Question 10.
Consider the structure of table Doctor given below:
Doctor_id(p)
Doctor_Name Hospital_id(F)
Joining_Date
Speciality
Salary
Experience
Write Python code to create the above table.
Answer:
import MySQLdb .
db = MySQLdb.connect(‘localhost’HosAdmin’,
‘HosAdmin0123′,’XYZHospital’ ) cursor=db.cursor()
cursor.execute (“DROP TABLE IF EXISTS DOCTOR”) sql=”””Create Table Doctor (‘Doctor_Id’ INT NOTNULL,
‘Doctor_Name’ Char(50) NOTNULL,
‘Hospital_Id’ INT NOTNULL,
‘Joining_Date’ Date NOTNULL,
‘Speciality’ Char (50),
‘Salary’ Float,
‘Experience’ Float,
Primary Key (‘Doctor_Id’))””” cursor.execute(sql) cursor.close() db.close()

Commonly Made Error:

• Few students get confused to import the correct DB – API module.

Answering Tips:

• Keep in mind to give user id and password while connecting to a database.
• Be sure to import the correct DB – API module.

Section – C
( 5 Marks Each)

Question 11.
Write SQL queries for (a) to (d) which are based on the tables Trainer given below:
Table: VEHICLE

VCODE	VEHICLE TYPE	PERKM
V01	VOLVO BUS	150
V02	AC DELUXE BUS	125
V03	ORDINARY BUS	80
V05	SUV	30
V05	CAR	18

Table: TRAVEL

CNO	CNAME	TRAVEL DATE	KM	VCODE	NOP
101	K. Niwal	2015-12-13	200	V01	32
103	Fredrick Sym	2016-03-21′	120	V03	45
105	Hitesh Jain	2016-04-23	450	V02	42
202	Ravi Anish	2016-01-13	80	V02	40
207	John Malina	2015-02-10	65	V04	2
104	Sahanubhuti	2016-01-28	90	V05	4
106	Ramesh Jaya	2016-04-06	100	V01	25

Note:
PERKM is Freight Charges per kilometer.
Km is kilometres travelled.
NOP is number of passengers travelled in vehicle.
(a) To display CNO, CNAME, TRAVELDATE from the table TRAVEL in descending order of CNO.
Answer:
SELECT CNO, CNAME, TRAVELDATE FROM TRAVEL ORDER BY CNO DESC;

(b) To display the CNAME of all customers from the table TRAVEL who are travelling by vehicle with code V01 or V02.
Answer:
SELECT CNAME FROM TRAVEL WHERE VCODE = ‘V01 ‘ OR VCODE =’V02’;

(c) To display the CNO and CNAME of those customers from the table TRAVEL who travelled between ‘2015-12-31’ and ‘2015-05-01’.
Answer:
SELECT CNO, CNAME FROM TRAVEL WHERE TRAVELDATE > = ‘2015-05-01’ AND TRAVELDATE< = ‘2015-12-31’;

(d) To display the different vehicle code from table vehicle.
Answer:
SELECT DISTINCT VCODE FROM TRAVEL;

Commonly Made Error:

• Some students do not write the ASC and DESC for increasing and decreasing order.

Answering Tip:

• Remember to mention the order in which to order a field i.e., Ascending/Descending

Question 12.
(a) Write two advantages and disadvantages of bus topology.
OR
Define the following:
Wide Area Network, VoIP
Answer:
Advantages:

• Easy to connect and install.
• Involves a low cost and installation time.

Disadvantages:

• The entire network shuts down if there is a failure in the connecting cable.
• Only a single message can travel at a particular time.

OR

A Wide Area Network (WAN) is a network that exists over a large scale geographical area. A WAN connects different smaller networks, including local area networks (LANs) and metropolitan area networks (MANs) VoIP (Voice over Internet Protocol) is a methodology and group of technologies for delivering voice communications and multimedia sessions over IP networks, such as the Internet.

Commonly Made Error:

• Some students get confused in different concept and write definition interchangeably.

Answering Tip:

• Students should learn all the concepts very carefully.

(b) What do you mean by packet switching?
Answer:
Packet Switching transmits data across digital networks by breaking it down into blocks or packets for more efficient transfer using various network devices. Each time one device sends a file to another, it breaks the file down into packets so that it can determine the most efficient route for sending the data across the network at that time.

Question 13.
Perfect Edu Services Ltd. is an educational organization. It is planning to setup its India campus at Karnataka with its head office at Delhi.
The Karnataka Campus has 4 main buildings – ADMIN, ENGINEERING, BUSINESS and MEDIA. You as a network expert have to suggest the best network related solutions for their problems raised in (a) to (d), keeping in mind the distances between the buildings and other given parameters. Shortest distances between various buildings:

Admin to Engineering	55 mt
Admin to Business	90 mt
Admin to Media	90 mt
Engineering to Business	55 mt
Business to Media	45 mt
Delhi Head office to Karnataka campus	2175 km

Number of computers installed at various buildings are as follows:

Admin	110
Engineering	75
Business	40
Media	40
Media	12
Delhi Head office	20

(a) Suggest the most appropriate location of the server inside the Karnataka campus to get the best connectivity for maximum no. of computers.
Answer:
Admin (Due to maximum number of computers)

(b) Draw the cable layout to efficiently connect various buildings within the Karnataka campus for connecting the computers.
Answer:

(c) Which hardware device will you suggest to be procured by the company to be installed to protect and control the internet uses within the campus?
Answer:
Firewall or Router

(d) Which will you suggest to establish the online face to face communication between the people in the admin office of Karnataka campus and Delhi Head office.
Answer:
Video Conferencing

Students can access the CBSE Sample Papers for Class 12 Computer Science with Solutions and marking scheme Term 2 Set 4 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Computer Science Term 2 Set 4 with Solutions

Time: 2 Hours
Maximum Marks: 35

General Instructions:

• The question paper is divided into 3 sections – A, B and C
• Section A, consists of 7 questions (1 – 7). Each question carries 2 marks.
• Section B, consists of 3 questions (8 – 10). Each question carries 3 marks.
• Section C, consists of 3 questions (11 – 13). Each question carries 4 marks.
• Internal choices have been given for question numbers 7, 8 and 12.

Section – A
(2 Marks Each)

Question 1.
Evaluate the following expressions:
(a) 6*3 + 4**2//5-8
Answer:
13

(b) 10 > 5 and 7 > 12 or not 18 > 3
Answer:
False

Question 2.
(i) Expand the following terms:
(a) PPP
Answer:
PPP : Point to Point Protocol

(b) FTP
Answer:
FTP : File Transfer Protocol

(ii) Name the transmission media best suitable for connecting to hilly areas.
Answer:
Microwave / Radio wave

Question 3.
What do you understand by Candidate Keys in a table? Give a suitable example of Candidate Keys from a table containing some meaningful data.
Answer:
A table may have more than one such attribute/group of attributes that identifies a tuple uniquely, all such attribute(s) are known as Candidate Keys.
Table: ITEM

Item_No	Item	Qty
101	Pen	500
102	Pencil	700
104	CD	500
109	DVD	700
105	Eraser	300
103	Duster	200

In the above table Item, Item No can be candidates keys.

Question 4.
Differentiate between fetchone() and fetchall() methods with suitable example for each.
Answer:

• fetchall() fetches all the rows of a query result.
• An empty list is returned if there is no record to fetch the cursor. fetchone() method returns one row or a single record at a time. It will return None if no more rows/records are available.

Question 5.
Write the output of the queries (a) to (d) based on the table Student given below:
Table: STUDENT

Roll_No	Name	Class	DOB	Gender	City	Marks
1	Nanda	X	06-06-1995	M	Agra	551
2	Saurabh	XII	07-05-1993	M	Mumbai	462
3	Sonal	XI	06-05-1994	F	Delhi	400
4	Trisla	XII	08-08-1995	F	Mumbai	450
5	Store	XII	08-10-1995	M	Delhi	369
6	Marisla	XI	12-12-1994	F	Dubai	250
7	Neha	X	08-12-1995	F	Moscow	377
8	Nishant	X	12-06-1995	M	Moscow	489

(a) SELECT COUNT(*), City FROM STUDENT GROUP BY CITY HAVING COUNT(*)>1;
Answer:

COUNT(*)	City
2	Mumbai
2	Delhi
2	Moscow

(b) SELECT MAX(DOB),MIN(DOB) FROM STUDENT;
Answer:

• MAX(DOB)
• 08-12-1995
• MIN(DOB)
• 07-05-1993

(c) SELECT NAME,GENDER FROM STUDENT WHERE CITY=”Delhi”;
Answer:

NAME	GENDER
Sonal	F
store	M

(d) SELECT NAME, MARKS FROM STUDENT WHERE CITY IN (“MUMBAI”, “DELHI”)
Answer:

NAME	MARKS
Sarubh	462
Sonal	400
Trisha	350
Store	469

Question 6.
(a) In SQL, name the clause that is used to display the tuples in ascending order of an attribute.
Answer:
ORDER BY Clause

(b) In SQL, what is the use of IS NULL operator?
Answer:
To check if the column has null value / no value.

Question 7.
Observe the following table Pro_Info carefully:
Table: Pro_Info

ID	Product	Qty	Price	Transaction_Date
101	Plastic Floder 12″	100	3400	2014-12-14
104	Pen stand standard	200	4500	2015-01-31
105	Stapler Medium	250	1200	2015-02-28
109	Punching Machine Big	200	1400	2015-03-12
103	Stapler Mini	100	1500	2015-02-02

(a) Write the names of the most appropriate columns, which can be considered as candidate keys.
Answer:
Candidate keys : Id, Product

(b) Write the names of the most appropriate columns, which can be considered as primary key. Justify your answer.
Answer:
Primary key : Id, because it will uniquely identify each record in the table.

OR

(a) Identify the degree and cardinality of the table Pro_info.
Answer:
Degree: 5, Cardinality: 5

(b) Consider the table TRANSPORT given below:
TRANSPORT

T_Code	ID	TType
T101	101	Bus
T102	104	Volvo
T103	105	Auto
T104	109	Train
T105	101	Truck
T106	103	Car

Which field will be consider as the foreign key if the tables Pro_Info and TRANSPORT are related in a database?
Answer:
Id

Sect ion – B
(3 Marks Each)

Question 8.
Write a function DeleteCustomer() to delete a Customer information from a list of CStack. The function delete the name of customer from the stack.
Or
Write a function to perform push and pop operations on a Stack containing Student details as given in the following
RNo integer
Name String
Age integer
Answer:
CStack = []
def DeleteCustomer(): if (CStack == [ ]) :
print(“There is no Customer!”) else:
print(“Record deleted:”,CStack.pop()) 3

OR

defstkPUSH(stk,item): stk.append(item) top=len(stk)-1 defstkPOP(stk): ifstk!=[]:
returnstk.pop()
else:
return None

Question 9.
(a) A table, “Customers” has been created in a database with the following fields:
CustomerlD, CustomerName, ContactName, Address City, PostalCode, Country Give the SQL command to updates the first customer (CustomerlD = 1) with a new contact person “Rachit” and a new city “Mumbai”.
Answer:
UPDATE Customers
SET ContactName = ‘Rachit’, City= ‘Mumbai’
WHERE CustomerlD = 1;

(b) What is the use of wildcard ? Give an example
Answer:
The wildcard operators are used with the LIKE operator to search a value similar to a specific pattern in a column. There are 2 wildcard operators.
% (Percent) – represents 0,1 or many characters
_ (Underscore) = represents a single number or character For example: Select * from Customer where name like ‘S%’;
This command will show all those records from table named Customer where name field contains values starting with S for e.g. Sri, Siya, Shyam, Suman, etc.

Question 10.
Sonakshi has to create a database named Publishers in MYSQL.
She now needs to create a table named Book in the database to store the records of various Books.
The table Book has the following structure:

Field Name	Data type	Remarks
BookCode	Char(3)	primary key
Book_Name	Char(30)
Pages	Integer
Price	Integer
Authbr_Name	Char(30)

Help her to complete the task by suggesting appropriate SQL commands.
Answer:
CREATE DATABASE Publishers;
CREATE TABLE Book (
Book_Code CHAR(5)PRIMARY KEY
f
Book_Name CHAR(30),
Pages INT,
Price INT,
Author_Name CHAR(30)
);

Section – C
(5 Marks Each)

Question 11.
Write queries (a) to (d) based on the tables TRAINER and COURSE given below:
TRAINER

TID	TNAME	CITY	HIREDATE	SALARY
101	Sunaina	Mumbai	1998-10-15	90,000
102	Anamika	Delhi	1994-12-24	80,000
103	Deepti	Chandigarh	2001-12-21	82,000
104	Meenakshi	Delhi	2002-12-25	78,000
105	Richa	Mumbai	1996-01-12	95,000
106	Maniprabha	Chennai	2001-12-12	69,000

COURSE

CID	CNAME	FEES	STARTDATE	TID
c201	AGDCA	12,000	2018-07-02	101
c202	ADCA	15,000	2018-07-15	103
c203	DCA	10,000	2018-10-01	102
c204	DDTP	9,000	2018-09-15	104
c205	DHN	20,000	2018-08-01	101
c206	O LEVEL	18,000	2018-07-25	105

(a) Display the Trainer Name, City & Salary in descending order of their Hiredate.
Answer:
SELECT TNAME, CITY, SALARY FROM TRAINER ORDER BY HIREDATE DESC;

(b) To display the TNAME and CITY of Trainer who joined the Institute in the month of December 2001.
Answer:
SELECT TNAME, CITY FROM TRAINER WHERE HIREDATE BETWEEN ‘2001-12- 01’ AND ‘2001-12-31’;

(c) To display the average salary of all trainer, city wise.
Answer:
SELECT AVG(SALARY) FROM TRAINER GROUP BY CITY;

(d) To display TNAME, HIREDATE, CNAME, STARTDATE from tables TRAINER and COURSE of all those courses whose FEES is less than or equal to 10000.
Answer:
SELECT TNAME,HIREDATE,CNAME, STARTDATE FROM TRAINER, COURSE WHERE
TRAINER.TID=COURSE.TID AND FEES<= 10000;

Question 12.
(a) Write two characteristics of Wi-Fi.
OR
Define the following:
HTML, XML
Answer:

• It is wireless network.
• It is used for short range.

OR

HTML (Hyper Text Markup Language): It is a markup language that describes the structure and behavior of a web page. This language is used to create web pages.
XML (Extensible Markup Language): It is a meta language that provides a framework to define the markup language.

(b) Explain the purpose of a router
Answer:
A router establishes connection between two networks and it can handle network with different protocols. Using a routing table, routers make sure that the data packets are travelling through the best possible paths to reach their destination.

Question 13.
Delhi University of India is starting its first campus Nagarjun Nagar of South India with its centre admission office in Mumbai. The university has three major branch comprising of Administrative Branch, Theory Branch and Practical Branch in the 5 km area campus.
As a network expert, you need to suggest the network plan as per (a) to (d) to the authorities keeping in mind the distance and other given parameters.

Expected wire distances between various locations:

Administrative Branch to Theory Branch	90 m
Administrative Branch to Practical Branch	80 m
Theory Branch to Practical Branch	15 m
Admission Office Mumbai to Nagarjun Campus	1600 km

Expected number of computers to installed at various locations in the university are as follows:

Administrative Branch	15
Theory Branch	40
Practical Branch	150
Admission Office Mumbai	10

(a) Suggest the authorities, the cable layout amongst various branches inside university campus for connecting the branches.
Answer:
The suggested cable layout amongst various blocks inside university campus for connecting the
blocks will be as follow:

(b) Suggest the most suitable place (i.e. branch) to house the server of this university with a suitable reason.
Answer:
Practical Branch, because in this branch there are maximum number of computer and according to 80 – 20 rule of 80% traffic should be local.

(c) Suggest an efficient device from the following to be installed in each of the branch to connect all the computers.
(i) Switch
(ii) Modem
(iii) Gateway
Answer:
Switch

(d) Suggest the most suitable (very high speed) service to provide data connectivity between Admission Office located in Mumbai and Nagarjun Nagar campus from the following options:
(i) Telephone lines
(ii) Fixed line dial-up connection
(iii) Co-axial cable network
(iv) GSM
(v) Leased lines
(vi) Satellite connection
Answer:
Satellite connection

Students can access the CBSE Sample Papers for Class 12 Computer Science with Solutions and marking scheme Term 2 Set 1 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Computer Science Term 2 Set 1 with Solutions

Time: 2 Hours
Maximum Marks: 35

General Instructions:

• The question paper is divided into 3 sections – A, B and C
• Section A, consists of 7 questions (1 – 7). Each question carries 2 marks.
• Section B, consists of 3 questions (8 – 10). Each question carries 3 marks.
• Section C, consists of 3 questions (11 – 13). Each question carries 4 marks.
• Internal choices have been given for question numbers 7, 8 and 12.

Section – A
(2 Marks Each)

Question 1.
Give any two characteristics of stacks.
Answer:
Characteristics of Stacks:

• The insertion and deletion happens at one end i.e. from the top of the stack
• Stack is a linear data structure based on LIFO (Last In First Out) order

Question 2.
(a) Expand the following:
SMTP , XML
Answer:

• SMTP: Simple Mail Transfer Protocol
• XML: Extensible Mark Up Language

(b) Out of the following, which is the fastest wired and wireless medium of transmission?
Infrared, coaxial cable, optical fibre, microwave, Ethernet cable
Answer:
Wired: Optical Fibre Wireless: Microwave

Question 3.
Differentiate between char(n) and varchar(n) data types with respect to databases.
Answer:
char(n):

•  Stores a fixed length string between 1 and 255 characters.
•   If the value is of smaller length, adds blank spaces.
•  Some space is wasted.

varchar(n):

• Stores a variable length string.
• No blanks are added even if value is of smaller length.
• No wastage of space.

Question 4.
A result set is extracted from the database using the cursor object (that has been already created) by giving the following statement.
My data = cursor. fetchone()
(a) How many records will be returned by fetchone() method?
Answer: One record

(b) What will be the datatype of Mydata object after the given command is executed?
Answer: Tuple

Question 5.
Write the output of the queries (a) to (d) based on the table, Furniture given below:

FID	NAME	DATE OF PURCHASE	COST	DISCOUNT
B001	Double Bed	03-Jan-2018	45000	10
T010	Dining Table	10-Mar-2020	51000	5
B004	Single Bed	19-Ju 1-2021	22000	0
C003	Long Back Chair	30-Dec-2016	12000	3
T006	Console Table	17-Nov-2019	15000	12
B006	Bunk Bed	01-Jan-2021	28000	14

(a) SELECT SUM (DISCOUNT)
FROM FURNITURE WHERE COST>15000;
Answer: 29

(b) SELECT MAX(DATEOFPURCHASE)
FROM FURNITURE;
Answer: 19 – July – 2021

(c) SELECT * FROM FURNITURE
WHERE DISCOUNTS AND FID LIKE “T%”;
Answer:

T006

Console Table

17-Nov-2019

15000

12

(d) SELECT DATEOFPURCHASE FROM FURNITURE
WHERE NAME IN (“Dining Table”, “Console Table”);
Answer:

• 10-Mar-2020
• 17-Nov-2019

Question 6.
a) Which command is used to view the list of tables in a database?
Answer:
SHOW TABLES;

(b) Give one point of difference between an equi-join and a natural join.
Answer:
Equi- join:

• The join in which columns from two tables are compared for equality.
• Duplicate columns are shown.

Natural Join:

• The join in which only one of the identical columns existing in both tables is present.
• No duplication of columns.

Question 7.
Consider the table, MOVIEDETAILS given below:
Table of MovieDetails

MOVIEID	TITLE	LANGUAGE	RATING	PLATFORM
M001	Minari	Korean	5	Netflix
M004	MGR Magan	Tamil	4	Hotstar
M010	Kaagaz	Hindi	3	Zee5
M011	Harry Potter and the Chamber of Secrets	English	4	Prime Video
M015	Uri	Hindi	5	Zee5
M020	Avengers: Endgame	English	4	Hotstar

(a) Identify the degree and cardinality of the table.
Answer:

• Degree: 5
• Cardinality: 6

(b) Which field should be made the primary key? Justify your answer.
Answer:
MOVIEID should be made the primary key as it uniquely identifies each record of the table.

OR

(a) Identify the candidate key(s) from the table MOVIEDETAILS.
Answer:
MOVIEID AND TITLE

(b) Consider the table SCHEDULE given below:
Table of Schedule

SLOTID	MOVIED	TIMESLOT
S001	M010	10 AM To 12PM
S002	M020	2PM To 5PM
S003	M010	6PM To 8PM
S004	M011	9PM To 11PM

Which field will be considered as the foreign key if the tables MOVIEDETAILS and SCHEDULE are related in a database.
Answer:
MOVIEID

Section – B
(3 Marks Each)

Question 8.
Julie has created a dictionary containing names and marks as key value pairs of 6 students. Write a program, with separate user defined functions to perform the following operations:

• Push the keys (name of the student) of the dictionary into a stack, where the corresponding value (marks) is greater than 75.
•  Pop and display the content of the stack.

For example:
If the sample content of the dictionary is as follows:
R ={“OM”:76, “JAI”:45, “BOB”:89, “ALI”:65, “ANU”:90,
The output from the program should be:
TOM ANU BOB OM

OR

Alam has a list containing 10 integers. You need to help him create a program with separate user defined functions to perform the following operations based on this list.

• Traverse the content of the list and push the even numbers into a stack.
• Pop and display the content of the stack.

For Example
If the sample Content of the list is as follows:
N=[12,13, 34,56,21, 79, 98,22, 35, 38]
Sample Output of the code should be:
38 22 98 56 34 12
Answer:
# Question No 8 (first option)
R={“OM”:7 6, “JAI”:45, “BOB”:89, “ALI”:65, “ANU”:90, “TOM”:82} def PUSH(S,N):
S.append(N) def POP(S): if S! = [] :
return S.popO else:
return None
ST=[]
for k in R:
if R[k]>=75:
PUSH(ST,k) while True: if ST!=[]:
print(POP(ST),end=” “) else:
break

OR

N = [12, 13, 34, 56, 21, 79, 98, 22, 35, 38] def PUSH(S,N):
S.append(N)
def POP (S) : .
if S!=[]:
return S.popO else:
return None
ST=[]
for k in N: if k%2==0:
PUSH(ST,k) while True:
if ST!=[]:
print (POP(ST),end=” “) else: break

Question 9.
(a) A table, ITEM has been created in a database with the following fields:
ITEMCODE, ITEMNAME, QTY, PRICE
Give the SQL command to add a new field, DISCOUNT (of type Integer) to the ITEM table.
Answer:
ALTER TABLE Item ADD (Discount INT);

(b) Categorize following commands into DDL and DML commands?
INSERT INTO, DROP TABLE, ALTER TABLE, UPDATE, SET
Answer:

• DDL: DROP TABLE, ALTER TABLE
• DML: INSERT INTO, UPDATE…SET

Question 10.
Charu has to create a database named MYEARTH in MYSQL.
She now needs to create a table named CITY in the database to store the records of various cities across the globe. The table CITY has the following structure:
Table: CITY

FIELD NAME	DATATYPE	REMARKS
CITY CODE	CHAR(5)	Primary Key
CITY NAME	CHAR(30)
SIZE	INTEGER
AVGTEMP	INTEGER
POLUTION RATE	INTEGER
POPULATION	INTEGER

Help her to complete the task by suggesting appropriate SQL commands.
Answer:
CREATE DATABASE MYEARTH;
CREATE TABLE CITY
(
CITYCODE CHAR(5)PRIMARY KEY,
CITYNAME CHAR(30),
SIZE INT,
AVGTEMP INT,
POPULATIONRATE INT,
POPULATION INT,
) ;

Section – C
(4 Marks Each)

Question 11.
Write queries (a) to (d) based on the tables EMPLOYEE and DEPARTMENT given below:
Table: EMPLOYEE

EMPID	NAME	DOB	DEPITED	DESIG	SALARY
120	Alisha	23-Jan-1978	D001	Manager	75000
123	Nitin	10-Oct-1977	D002	AO	59000
129	Navjot	12-Jul-1971	D003	Supervisor	40000
130	Jimmy	30-Dec-1980	D004	Sales Rep
131	Faiz	06-Apr-1984	D001	Dep Manager 65000

Table: DEPARTMENT

DEPITED	DEPTNAME	FLOOORNO
D001	Personal	4
D002	Admin	10
D003	Production	1
D004	Sales	3

(a) To display the average salary of all employees, department wise.
Answer:

• SELECT AVG (SALARY)
• FROM EMPLOYEE
• GROUP BY DEPTID;

(b) To display name and respective department name of each employee whose salary is more than 50000.
Answer:

• SELECT NAME, DEPTNAME FROM EMPLOYEE, DEPARTMENT WHERE
• EMPLOYEE.DEPTID=
• DEPARTMENT.DEPTID
• AND SALARY>50000;

(c) To display the names of employees whose salary is not known, in alphabetical order.
Answer:

• SELECT NAME FROM EMPLOYEE
• WHERE SALARY IS NULL
• ORDER BY NAME;

(d) To display DEPTID from the table EMPLOYEE without repetition.
Answer:
SELECT DISTINCT DEPTID FROM EMPLOYEE;

Question 12.
(a) Give two advantages and two disadvantages of star topology.
OR
Define the following terms: WWW, Web hosting
Answer:
Advantages

• Ease of service.
• Centralized control.
• Easy to diagnose faults.
• One device per connection.

Disadvantages

• Long cable length.
• Difficult to expand.
• Central node dependency.

OR

WWW: A set of protocols that allow you to access any document on the internet through the naming systems based on URLs.
Web hosting:
Web hosting is a service that allows organizations and individuals to post a website or web page onto the server, which can be viewed by everyone on the Internet.

(b) How is Packet Switching different from Circuit Switching?
Answer:
Packet switching:

• Uses store and forward concept to send messages.
• No physical path is actually establishes.
• Message is divided into smaller parts, known as packets and then sent forward.
• Tight upper limit on block size.
• Each data unit knows only the final receiver’s address.

Circuit switching:

• Physical connection is established between sender and receiver.
• Each data unit knows the entire path from sender to receiver.
•  It does not follow store and forward concept.

Question 13.
Be Happy Corporation has set up its new centre at Noida, Uttar Pradesh for its office and web-based activities. It has 4 blocks of buildings.

Distance between the various blocks is as follows:
A to B    40 m
B to C     120 m
C to D     100m
A to D     170m
B to D     150m
A to C     70m
Numbers of computers in each block
Block A    25
Block B    50
Block C    125
Block D    10
(a) Suggest and draw the cable layout to efficiently connect various blocks of buildings within the Noida centre for connecting the digital devices.
Answer:

(b) Suggest the placement of the following device with justification:
(i) Repeater
(ii) Hub/Switch
Answer:

• Repeater: between C and D as the distance between them is 100 mts.
• Hub/ Switch: In each block as they help to share data packets within the devices of the network in each block.

(c) Which kind of network (PAN/LAN/WAN) will be formed if the Noida office is connected to its head office in Mumbai?
Answer:
WAN

(d) Which fast and very effective wireless transmission medium should preferably be used to connect the head office at Mumbai with the centre at Noida?
Satellite