KENDRIYA VIDYALAYA SANGATHAN HYDERABAD REGION

PRE-BOARD - EXAMINATION - 2020-21

Class: XII Max Marks:70
Subject:Computer Science Time: 3 hours

General Instructions:
1. This question paper contains two parts A and B. Each part is compulsory.
2. Both Part A and Part B have choices.
3. Part-A has 2 sections:
a. Section – I is short answer questions, to be answered in one word or one line.
b. Section – II has two case studies questions. Each case study has 4 case-based subparts.
An examinee is to attempt any 4 out of the 5 subparts.
4. Part - B is Descriptive Paper.
5. Part- B has three sections
a. Section-I is short answer questions of 2 marks each in which two question have
internal options.
b. Section-II is long answer questions of 3 marks each in which two questions have
internal options.
c. Section-III is very long answer questions of 5 marks each in which one question has
internal option.
6. All programming questions are to be answered using Python Language only

Q.No Part-A Marks

Section-I
Attempt any 15 questions from question no 1 to 21.
1 Write the output of the following python statements: 1
Array=[8,5,3,2,1,1]
print(Array[-1:-6:-1])
2 Which one is valid assignment operator in Python 1
i. / ii. = iii. = = iv. and
3 Which of the following can be used as valid variable identifiers in Python? 1
i) 4th Sum ii) Total iii) Number# iv) _Data
4 Find the operator which cannot be used with a string in Python from the 1
following: (a) + (b) in (c) * (d) //
5 Consider the tuple in python named DAYS= (”SUN”,”MON”,”TUES”). 1
Identify the invalid statement(s) from the given below statements:
1. S=DAYS[1]
2. print(DAYS[2])
3. DAYS[0]=”WED”
4. LIST=list(DAYS)

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6 Write a statement in Python to declare a dictionary whose keys are 1, 2, 3 1
and values are Monday, Tuesday and Wednesday respectively.
7 Identify the valid declaration of L: 1
L = (‘Mon’, ‘23’, ‘hello’, ’60.5’)
a. dictionary b. string c. tuple d. list
8 ..................... method of pickle module is used to read data from a binary file. 1
(a) read( ) b) load( ) c) dump( ) d) readlines( )
9 Expand the term 1
i. URL ii. HTTPS
10 A device used to connect dissimilar networks is called ................................ . 1
i. Modem ii. Gateway iii. Bridge iv. hub
11 Which of the following is NOT a DML Command. 1
i) Insert ii) Update iii) Drop iv) Delete
12 In SQL ,what command is used to describe the table structure? 1
13 Identify the error in the following SQL query which is expected to delete all 1
rows of a table TEMP without deleting its structure and write the correct one:
DELETE TABLE TEMP;
14 A relation has 5 rows & 5 columns, later two more rows were added to the 1
relation .What will be the Degree & Cardinality of that relation?
i. Degree 5, Cardinality 7
ii. Degree 7, Cardinality 5
iii. Degree 50, Cardinality 7
iv. Degree 5, Cardinality 5
15 Website in charge KABIR of a school is handling downloading/uploading 1
various files on school website. Write the name of the protocol which is being
used in the above activity.
16 Which statement is used to retrieve the current position within the file? 1
a) fp.seek( ) b) fp.tell( ) c) fp.loc d) fp.pos
17 Name the Python Library modules which need to be imported to invoke the 1
following functions:
(i) sin( ) (ii) random ( )
18 In SQL, which clause is used to remove duplicate records of a table while 1
display?
i) or ii) distinct iii) any iv)unique

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19 Identify the Guided and Un-Guided Transmission Media out of the following: 1
Satellite, Twisted Pair Cable, Optical Fiber, Infra-Red waves
20 Which clause is used in query to place the condition on groups in MySql? 1
i) where ii) having iii) group by iv) none of the above
21 What is GSM? 1
Section-II
Both the case study based questions are compulsory. Attempt any 4 subparts from each
question. Each question carries 1 mark.
22 A CD/DVD Shop named “NEW DIGITAL SHOP” stores various CDs & 4
DVDs of songs/albums/movies and use SQL to maintain its records. As a
Database Administrator, you have decided the following:
• Name of Database - CDSHOP
• Name of Relation - LIBRARY
• Attributes are:-
(a) CDNO - Numeric values
(b)NAME - Character values of size (25)
(c) QTY - Numeric values
(d)PRICE - Decimal values

Answer the following questions based on the above table LIBRARY:-

a) Display all the details of the table whose quantity is more than 20 .
b) Identify the best attribute which may be declared as Primary key.
c) Insert the following record in the above relation: (10009,
”Motivational Songs”, 15, 70)
d) Write an SQL query to display the minimum quantity.
e) Database administrator wants to count the no. of CDs which does not
have any Price value. Write the query for the same.
23 Suresh is writing a program to create a CSV file “files.csv” which will contain 4
filetypes and file extensions for some records. He has written the following

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 code. As a programmer, help him to successfully execute the given task.
import --------------------- # Line 1
def addinFile(filetype,extension): # to write /add data into the file

f=open('-----------------','-----------') # Line 2
newFileWriter = csv.writer(f)
newFileWriter.writerow([filetype,extension])
f.close()
#csv file reading code

def readFile(filename): # to read data

from CSV with open(filename,'r') as nf:
nfr = csv._________(nf) # Line 3
for row in nfr:
print (row[0],row[1])
nf.____________ # Line 4
addinFile(“C++”,”.cpp”)

addinFile(“Python”,”.py”)
addinFile(“Java”,”.java”)
addinFile(“Microsoft Excel”,”.xls”)
readFile(………….) #Line 5
Answer the following questions: (1 mark each)
(a) Name the module he should import in Line 1.
(b) Fill in the blank to open file and In which mode, Suresh should open
the file to add data into the file
(c) Fill in the blank in Line 3 to read the data from a csv file.
(d) Fill in the blank in Line 4 to close the file.
(e) Fill in the blank in line 5 to send the file name as parameter .

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 Part-B
Section-I
24 Find the output of the following program: 2
def increment(n):
n.append([4])
return n
l=[1,2,3]
m=increment(l)
print(l,m)
25 Differentiate between SMTP & POP3. 2
OR
List any two security measures to ensure network security.
26 Rohit has purchased a new Smart TV and wants to cast a video from his 2
mobile to his new Smart TV. Identify the type of network he is using and
explain it.
27 What is the meaning of return value of a function? Give an example to 2
illustrate its meaning.
OR
Differentiate between a positional and default arguments with the help of an
example.
28 Rewrite the following code after removing syntax error and underline the 2
correction:
Y=integer(input(“Enter 1 or 10”))
if Y==10
for Y in range(1,11):
print(Y)
else:
for m in range(5,0,-1):
print(thank you)
29 What possible output(s) are expected to be displayed on screen at the time of 2
execution of the program from the following code? Also specify the
maximum values that can be assigned to each of the variables start and end.
import random
ar=[20,30,40,50,60,70]
start=random.randint(0,2)
end=random.randint(2,4)
for k in range(start,end):
print(ar[k],end=”#”)
(i) 30# (iii) 10#20#30#40#50#

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 (ii) 20#30 (iv) 40#30#
30 What do you understand by Candidate Keys in a table? Give a suitable 2
example of Candidate Keys from a table containing some meaningful data.
31 Answer the following questions : 2
1. Which package must be imported in python to create a database
connectivity application?
2. Which method is used for Connecting SQL with Python?
32 Differentiate between Alter and update TABLE command. 2
33 Predict the output for following code. 2
def myfunc(str1):
rstr=' '
index=len(str1)
while(index > 0):
if str1[index-1].isalpha():
rstr+=str1[index-1]
else:
rstr+='@'
index=index-1
return rstr
print(myfunc('a1b2c3d4'))
Section II
34 Write a function in python named SwapHalfList(Array), which accepts a list 3
Array of numbers and swaps the elements of 1st Half of the list with the 2nd
Half of the list ONLY if the sum of 1st Half is greater than 2nd Half of the
list.
Sample Input Data of the list Array= [ 100, 200, 300, 40, 50, 60],
Output Arr = [40, 50, 60, 100, 200, 300]
35 Write a method/function COUNTLINES_ET() in python to read lines from a 3
text file REPORT.TXT, and COUNT those lines which are starting either
with ‘E’ and starting with ‘T’ respectively. And display the Total count
separately.
For example: if REPORT.TXT consists of
“ENTRY LEVEL OF PROGRAMMING CAN BE LEARNED FROM
PYTHON. ALSO, IT IS VERY FLEXIBLE LANGUGAE. THIS WILL BE
USEFUL FOR VARIETY OF USERS.”
Then, Output will be:

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 No. of Lines with E: 1
No. of Lines with T: 1
OR

Write a method/function SHOW_TODO() in python to read contents from a

text file ABC.TXT and display those lines which have occurrence of the word
‘‘TO’’ or ‘‘DO’’. For example : If the content of the file is
“THIS IS IMPORTANT TO NOTE THAT SUCCESS IS THE RESULT OF
HARD WORK. WE ALL ARE EXPECTED TO DO HARD WORK. AFTER
ALL EXPERIENCE COMES FROM HARDWORK.”
The method/function should display:
• THIS IS IMPORTANT TO NOTE THAT SUCCESS IS THE RESULT OF
HARD WORK.
• WE ALL ARE EXPECTED TO DO HARD WORK.
36 Table : Employee 3
EmployeeId Name Sales JobId
E1 Sumit Sinha 110000 102
E2 Vijay Singh Tomar 130000 101
E3 Ajay Rajpal 140000 103
E4 Mohit Kumar 125000 102
E5 Sailja Singh 145000 103
Table: Job
JobId JobTitle Salary
101 President 200000
102 Vice President 125000
103 Administrator Assistant 80000
104 Accounting Manager 70000
105 Accountant 65000
106 Sales Manager 80000
Give the output of following SQL statement:
(i) Select max(salary),min(salary) from job;
(ii) Select Name, JobTitle, Sales from Employee, Job
where Employee. JobId=Job. JobId and JobId in (101,102)
(iii) Select JobId, count(*) from Employee group by JobId

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37 Write a function in python named PUSH(STACK, SET) where STACK is list 3
of some numbers forming a stack and SET is a list of some numbers. The
function will push all the EVEN elements from the SET into a STACK
implemented by using a list. Display the stack after push operation.
OR
Write a function in python named DEL(QUEUE) where QUEUE is
implemented by a list of numbers. The function will display the DELETED
element .
Section-III
38 Quick Learn University is setting up its academic blocks at Prayag Nagar and 5
planning to set up a network. The university has 3 academic blocks and one
human resource Centre as shown in the diagram given below:

Technology
Business
Block

Law Block HR Block

Centre-to-Centre distance between various blocks is as follows:

Law block to business block 40 m
Law block to technology block 80 m
Law block to HR block 105 m
Business block to technology block 30 m
Business block to HR block 35 m
Technology block to HR block 15 m
Number of computers in each of the buildings is as follows:
Law block 15
Technology block 40
HR Block 115
Business block 25
(a) Suggest a cable layout of connection between the blocks.
(b) Suggest the most suitable place to house the server of the organization
with suitable reason.

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 (c) Which device should be placed/ installed in each of these blocks to
efficiently connect all the computers within these blocks?
(d) The university is planning to link its sales counters situated in various
parts of the other cities. Which type of network out of LAN, MAN or WAN
will be formed?
(e) Which type of network topology may be preferred between these blocks?
39 Write SQL Commands for the following queries based on the relations 5
PRODUCT and CLIENT given below.
Table: Product
P_ID ProductName Manufacturer Price ExpiryDate
TP01 Talcum Powder LAK 40 2011-06-26
FW05 Face Wash ABC 45 2010-12-01
BS01 Bath Soap ABC 55 2010-09-10
SH06 Shampoo XYZ 120 2012-04-09
FW12 Face Wash XYZ 95 2010-08-15
Table: Client
C_ID ClientName City P_ID
1 Cosmetic Shop Delhi FW05
6 Total Health Mumbai BS01
12 Live Life Delhi SH06
15 Pretty One Delhi FW05
16 Dreams Bengaluru TP01
14 Expressions Delhi NULL
(i) To display the ClientName and City of all Mumbai- and Delhi-based
clients in Client table.
(ii) Increase the price of all the products in Product table by 10%.
(iii) To display the ProductName, Manufacturer, ExpiryDate of all the
products that expired on or before ‘2010-12-31’.
(iv) To display C_ID, ClientName, City of all the clients (including the
ones that have not purchased a product) and their corresponding
ProductName sold.
(v) To display productName, Manufacturer and ClientName of Mumbai
City.
40 (a) Create a binary file “employee.dat” that stores the records of employees 5

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 and display them one by one.
(b) Display the records of all those employees who are getting salaries
between 25000 to 30000.
OR
A binary file “CLUB.DAT” has structure (PNO, PName, Game,Fee).
The description is given below:
PNo : Player Number e.g. 365478
PName : Player Name e.g. “Rajat”
Game : Game of Player e.g. “Basketball”
Fee : Coaching Fee e.g.12500.00

Write a function Player_Count() in Python that would read contents of the

file “CLUB.DAT” and display the details of those players whose fee is above
7500. Also display number of players paying fee above 10000

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