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KENDRIYA VIDYALAYA SANGATHAN, KOLKATA REGION

FIRST PRE BOARD EXAMINATION [2019-20]
COMPUTER SCIENCE (083)
CLASS-XII
Time: 3 hrs Max. Marks: 70

General Instructions:
•Question paper is divided into 4 sections A, B, C and D.
•Section A: Unit-1, Section B: Unit-2, Section C: Unit-3 and Section D: Unit-4
•Use Python language to exemplify your answers.

SECTION-A
1. (a) Write the valid identifier in the following: 1
(i) My.File (ii) My-File (iii) 2um (iv) pie
(b) Write the type of tokens from the following: 1
(i) 12.6 (ii) False
(c) Name the Python Library modules which need to be imported to invoke the 1
following functions:
(i) ceil( ) (ii) randint( )
(d) Rewrite the following code in python after removing all syntax error(s). 2
Underline each correction done in the code.
250 = Number
WHILE Number <= 1000:
if Number => 750:
print Number
Number = Number + 100
else
print Number*2
Number = Number + 50
(e) Find and write the output of the following python code: 2
for Name in ['Jayes', 'Ramya', 'Taruna', 'Suraj'] :
print(Name)
if Name[0] == 'T':
break
else :
print ('Finished!')
print ('Got it!')
(f) Find and write the output of the following python code: 3
Numbers = [9, 18, 27, 36]
for Num in Numbers:

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for N in range(1, Num%8) :

print(N, "#", end = "\n")
(g) What possible output(s) are expected to be displayed on the screen at the 2
time of execution of the program from the following code?
import random
print( 100 + random.randint(5,10), end = " ")
print( 100 + random.randint(5,10), end = " ")
print( 100 + random.randint(5,10), end = " ")
print( 100 + random.randint(5,10))
(i)102 105 104 105 (ii)110 103 104 105
(iii)105 107 105 110 (iv) 110 105 105 110
2. (a) What are the process of giving comments in a python program? 1
(b) Which is the correct form of declaration of tuple? 1
(i) Month = [‘January’, ’February’, ’March’]
(ii) Month = (‘January’, ’February’, ’March’)
(iii) Month = {1:‘January’, 2:’Feburary’, 3:’March’}
(iv) Month = (‘January’, ’February’, ’March’]
(c) Identify the valid declaration of d1: 1
d1 = { 5:’number’,\
‘a’:’string’,\
(1,2):’tuple’}
(i)List (ii) array (iii) tuple (iv) dictionary
(d) Find and write the output of the following python code: 1
x = 45
while x<50:
print(x)
(e) Find and write the output of the following python code: 1
def state1():
global tigers
tigers =15
print(tigers)
tigers =95
print(tigers)
state1()
print(tigers)
(f) What is the difference between a local variable and global variable? Also, 2
give a suitable python code to illustrate both.
(g) Write codes to plot following bar chart showing black bars: 2

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OR
Give the output from the given python code:
import matplotlib.pyplot as plt
import numpy as np
label = ['Anil', 'Vikas', 'Dharma','Mahen', 'Manish', 'Rajesh']
per = [94,85,45,25,50,54]
index = np.arange(len(label))
plt.bar(index, per, color = 'Black')
plt.xlabel('Student Name', fontsize = 15)
plt.ylabel('Percentage', fontsize = 15)
plt.xticks(index, label, fontsize = 10, rotation = 20)
plt.title('Percentage of Marks achieved by student of Class XII')
plt.show()
(h) A text file contains alphanumeric text (say an.txt). Write a program that reads 2
this text file and prints only the numbers or digits from the file.
OR
Write a function remove_lowercase( ) that accepts two filenames, and copies
all lines that do not start with a lowercase letter from the first file into the
second.
(i) Write a recursive function in python to implement binary search algorithm. 3
OR
Write a recursive code to compute and print sum of squares of n numbers.
Value of n is passed as parameter.
(j) Write a function in Python, to delete an element from a sorted list. 4
OR
Write the functions in Python push (stk, item ) and pop(stk) to check whether
the stack is empty, to add a new item, to delete an item and display the stack
respectively.

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SECTION-B
3. Questions 3(a) to 3(d): Fill in the blanks
(a) FM is the acronym for ___________________ 1
(b) _____________ is a technology that connects the things of daily use with 1
internet over wired or wireless connections.
(c) _______________ is a network device that connects dissimilar networks. 1
(d) _______________ is a specific condition in a network when more data 1
packets are coming to network devices than they can handle and process at a
time.
(e) Give the full forms of the following: 2
(i) POP (ii) IMAP (iii) CSMA/CA (iv) TCP/IP

(f) How many wires are there in twisted pair cable (Ethernet)? What is the name 2
of connector which is used to connect it with Ethernet port?

(g) Identify the type of cyber crime for the following situations: 3
i. Stalking by means of calls, messages, etc.
ii. A criminal installed confidentially a small device on the debit card
insertion section of ATM machine, to steal the information during a
legitimate ATM transaction. As the card is swiped at the machine, the
device captures the information stored on the card's magnetic strip.
iii. Continuously sending bulk requests to a website so that it is not
available to any other user.
(h) Jonathan and Jonathan Training Institute is planning to set up its center in 4
Amritsar with four specialized blocks for Medicine, Management, Law
courses along with an Admission block in separate buildings. The physical
distances between these blocks and the number of computers to be installed
in these blocks are given below. You as a network expert have to answer the
queries raised by their board of directors as given in (i) to (iv).

Shortest distances between various locations in meters:

Admin Block to Management Block 60

Admin Block to Medicine Block 40

Admin Block to Law Block 60

Management Block to Medicine Block 50

Management Block to Law Block 110

Law Block to Medicine Block 40

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Number of Computers installed at various locations are as follows:

Admin Block 150

Management Block 70

Medicine Block 20

Law Block 50

(i). Suggest the most suitable location to install the main server of this
institution to get efficient connectivity.
(ii). Suggest by drawing the best cable layout for effective network
connectivity of the blocks having server with all the other blocks.
(iii). Suggest the devices to be installed in each of these buildings for
connecting computers installed within the building out of the following:
 Modem
 Switch
 Gateway
 Router
(iv) Suggest the most suitable wired medium for efficiently connecting each
computer installed in every building out of the following network cables:
 Coaxial Cable
 Ethernet Cable
 Single Pair
 Telephone Cable.
SECTION-C
4 (a) Which keyword is used to select tuples containing a field that match a 1
wildcard pattern?
(b) Which clause is used to select specific rows in a table based on a condition. 1
(c) Which command is used to change the number of columns in a table? 1
(d) Which function is used to check whether MySQL Python connection is 1
successfully established?
(e) Differentiate between CHAR and VARCHAR data types? 2
OR
Differentiate between UNIQUE and DEFAULT constraints.
(f) What are the two types of HTTP requests in Django Web Framework? 2
(g) Write a output for SQL queries (i) to (iii), which are based on the table given 3

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below:
Table: SPORTS
Rno Class Name Game1 Grade1 Game2 Grade2

10 7 Sammer Cricket B Swimming A

11 8 Sujit Tennis A Skating C

12 7 Kamal Swimming B Football B

13 7 Venna Tennis C Tennis A

14 9 Archana Basketball A Cricket A

15 10 Arpit Cricket A Athletics C

i. SELECT COUNT(*) FROM SPORTS WHERE NAME LIKE ‘%a%’;

ii. SELECT MAX(Class) FROM SPORTS WHERE Grade1=Grade2;
iii. SELECT COUNT(*) FROM SPORTS GROUP BY Game1;
(h) Write SQL queries for (i) to (iv), which are based on the table SPORTS given in 4
the question 4(g):
i. Display the names of the students who have grade ‘A’ in either Game1
or Game2 or both.
ii. Display the number of students opted for the game ‘Cricket’
iii. Display the names of students who have same game for both Game1
and Game2.
iv. Display the games taken by the students whose name starts with ‘A’
SECTION-D
5. (a) This issue means stealing someone else’s intellectual work and representing 1
it as your own work without citing the source of information. Write the name
of this ethical issue.
(b) What is dismantling operation in recycle and recovery of e-waste? 1
(c) Posing as someone else online and using his/her personal/financial 2
information shopping online or posting something is a common type of cyber
crime these days:
i. What are such types of cyber-crimes collectively called?
ii. What measures can you take to stop these?
(d) Define this terms: (i) Phishing (ii) Computer Forensics 2
(e) Mr. Jayanto Das is confused between Shareware and Open source software. 2
Mention at least two points of differences to help him understand the same.
(f) What are gender and disability issues faced while teaching / using computer 2
in classrooms?