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CBSE Class 12 Pre Board 2021 : Computer Science - Set 2 (CBSE Gulf Sahodaya Qatar Chapter, Doha)

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PRE-BOARD EXAMINATION-2020-21 SUBJECT - COMPUTER SCIENCE Class: XII (CBSE) Date . Total Marks: 80 Time: 3 hrs. 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 sub- parts. 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 internal options have. 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 Question No. Marks PART-A SECTION-I Select the most appropriate option out of the options given for each question. Attempt any 15 questions from question no 1 to 21. 1. 2. 3. 4. 5. Find the invalid identifier from the following a) else b) 4rth_class c) _sum_of_nos 1 d) simple_intrest Given the lists L=[20,31,64,12,50,17,21,82] , write the output of print(L[3:6]) What is a CSV file? 1 1 Identify the valid arithmetic operator in Python from the following. a) or b) >= c) ? d) ** Suppose a tuple T is declared as T = (45, 56, 24, 78), which of the following is 1 1 incorrect? a) print(T[2]) Page 1 of 10 b) T[3] = -77 c) print(min(T)) d) print(len(T)) 6. Write a statement in Python to declare a dictionary whose keys are Sam, Syed, 1 Ahmad, Dilip and values are 88, 79 , 56 and 100 respectively. 7. A tuple is declared as 1 T = ( 3, 10, 13, 5, 4), What will be the value of sum(T) 8. Name the built-in mathematical function / method that is used to return an 1 absolute value of a number. 9. Name the protocol that is used to exchange large files across Internet. 1 10. What is the wrongful appropriation and stealing and publication of another 1 author s language, thoughts, ideas, or expressions and the representation of them as one s own original work called as? 11. Name The transmission media best suitable for fastest communication in LAN 1 12. Identify the valid declaration of T: T = (99, flower , green , 78.9, 100 , yellow , 89.50 , 128 ) 1 a. dictionary 13. b. string c .tuple d. list If the following code is executed, what will be the output of the following code? 1 name="CentralBoardOfSchoolExamination" print(name[4:15]) 14. In SQL, write the query to show the structure of table which include name of the column, data-type of column and the nullability which means, that column can contain null values or not. 1 15. Write the expanded form of SMTP. 1 16. Which of the following types of table constraints will prevent the entry of 1 duplicate rows? 17. a) Primary Key b) NOT NULL c) Duplicate d) Distinct e) Foreign Key Write the purpose of ipconfig command 1 Page 2 of 10 SECTION-II Both the Case study based questions are compulsory. Attempt any 4 sub parts from each question. Each question carries 1 mark 18. An Educational Institution, edtech is considering to maintain their database using 4 SQL to store the data. As a database administer, Salim has decided that Name of the database - edtechDB Name of the table - studentTb The attributes of studentTb are as follows: StdntId numeric StdntName text of size 30 StdntDOB - date type AnnualFee numeric a. Identify the attribute best suitable to be declared as a primary key b. Write the degree and cardinality of the table studentTb. c. Insert the following data into the attributes StdntId , StdntName StdntDOB and AnnualFee respectively in the given table studentTb. StdntId = 2000, StdntName = Saira, StdntDOB = 2009-12-12 and AnnualFee = 2500 d. Salim want to remove the table studentTb from the database edtechDB. Write the query to do it. Page 3 of 10 e. Now Salim wants to display the structure of the table studentTb, i.e, name of the attributes and their respective data types that he has used in the table. Write the query to display the same 19. Abhishek Nanda is writing a program to create a CSV file sales.csv which will 4 contain productName(P_Name), productCostPrice(P_CP) and productSellingPrice (P_SP )for some entries. He has written the following code. As a programmer, help him to successfully execute the given task. import # Line 1 def addSalesData(P_Name, P_CP, P_SP): # write data into file myfile=open(' sales.csv',' ') # Line 2 writerObj = csv.writer(myfile) writerObj.writerow([P_Name, P_CP, P_SP]) myfile.close() #csv file reading code def readSalesData (): # to read data from CSV file with open(' sales.csv','r') as myFile : readerObj = csv._______________(myFile) # Line 3 for rec in readerObj : print (rec[0],rec[1],rec[2]) myFile ._____________ # Line 4 addSalesData( Laptop Dell , 5000 , 5500 ) addSalesData (( Macbook , 8000 , 8500 ) addSalesData ( Microsoft Notebook , 4000 , 4500 ) readSalesData( ) #Line 5 a. Name the module he should import in Line 1. b. In which mode, Abhishek Nanda 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. Write the output he will obtain while executing Line 5. Page 4 of 10 PART B SECTION-I 20. Evaluate the following expressions: 2 a) X = 2* 3/ 5 + 10 //3 2**3 b) 20 <= 12 or 30 < 12 and not 20 < 50 and 55>20 21. Daniel has to share the data among various computers of his two offices branches situated in the same city. In addition, wants to use the internet efficiently in his organization: 2 a. Name the network (out of LAN, WAN, PAN and MAN) which is being formed in this process. b. What are the enabling technologies of IoT system that he should use OR Differentiate between IPV4 and IPV6? 22. Expand the following terms: a. TCP/IP 23. b. VoIP 2 c. WAN d. SMTP Write a program that creates a function swap_values(a,b) to swap the values 2 of two variables and show how it differs the values of variable inside the actual and formal parameters. If you display the values before function call and then after function call, what will be the difference? OR Explain the use of global key word used in a function with the help of a suitable example 24. Rewrite the following code in Python after removing all syntax error(s). 2 Underline each correction done in the code. 30=x For I in range(2,6) if x>30: print( true ) else Print( False ) 25. What possible outputs are expected to be displayed on the screen at the time of execution of the program from the following code? Also, specify the minimum and maximum values that can be assigned to the variable c. import random temp=[10,20,30,40,50,60] 2 Page 5 of 10 c=random.randint(0,4) for I in range(0, c): print(temp[i], # ) (i) 10#20# 26. 27. 28. (ii) 10#20#30#40#50# (iii). 10#20#30# (iv) 50#60# Differentiate between fetchone() and fetchall() methods with suitable examples for each. Explain DDL and DML commands in SQL, Give some examples of each type of commands Find and write the output of the following Python code: s = 'school2@com' k=len(s) m=" " 2 2 2 for i in range(0,k): if(s[i].isupper()): m=m+s[i].lower() elif s[i].isalpha(): m=m+s[i].upper() else: m=m+'bb' print(m)) SECTION- II 29. Write a function RShift(Arr,n) in Python, which accepts a list Arr of numbers and 3 n is a numeric value by which all elements of the list are shifted to right. Sample Input Data of the list : Arr= [ 15,25,35,45,50,33,41], n=2 Output Arr = [33,41,15,25,35,45,50] 30. A text file Quotes.Txt has the following data written in it: 3 Living a life you can be proud of Doing your best Spending your time with people and activities that are important to you Standing up for things that are right even when it s hard Becoming the best version of you Write a user defined function to display the total number of words present in the file Page 6 of 10 The output of the function should be: Total Number of Words in the file are: 4 OR Write a function AlphaCount() in Python, which should read each character of a text file Quotes.TXT, should count and display the occurrence of alphabets i and y (including small and capital cases). Example: If the file content is as follows: Living a life you can be proud of I do my best and all of you are doing your best The EUCount() function should display the output as: i or I : 5 y or Y : 4 31. Write the outputs of the SQL queries (i) to (iii) based on the relations Teacher 3 and Posting given below based on on a table COMPANY and CUSTOMER i. ii. SELECT COUNT(*) ,CITY FROM COMPANY GROUP BY CITY; SELECT MIN(PRICE), MAX(PRICE) FROM CUSTOMER WHERE QTY>10 ; Page 7 of 10 iii. 32. SELECT PRODUCTNAME,CITY, PRICE FROM COMPANY,CUSTOMER WHERE COMPANY.CID=CUSTOMER.CID AND PRODUCTNAME= MOBILE ; Write a function in Python PUSH(Arr), where Arr is a list of numbers given 3 by user at runtime. From this list push all numbers who are even into a stack implemented by using a list. Display the stack if it has at least one element, otherwise display appropriate error message if the list is empty. OR Write a function in Python POP(Arr), where Arr is a stack implemented by a list of numbers. The function returns the value deleted from the stack. Delete the stack element if it has at least one element, otherwise display appropriate underflow error message if the list is empty SECTION- III 33. Shah Medicos Center has set up its new center in Dubai. It has four buildings as shown in the diagram given below: 5 Distance between various building are as follows Page 8 of 10 As a network expert, provide the best possible answer for the following queries: i. Suggest a cable layout of connections between the buildings. ii. Suggest the most suitable place (i.e. buildings) to house the server of this organization. iii. Which device will you suggest to be placed/installed in each of these blocks/buildings to efficiently connect all the computers within these blocks/buildings iv. Suggest the placement of a Repeater in the network with justification. v. Suggest a system (hardware/software) to prevent unauthorized access to or from the network. 34. Study the following table and write the SQL commands for the following 5 queries (i) to (v) given at the end Table Doctors DocID DocName Department 101 M.Panday ENT TTS 102 G.P.Gupta Paed. MWF 201 C.K.Sharma Ortho SWF 301 M.N N arayN ENT TTS 302 P.K S harmA Ortho Table Patients TWF Pat_no PatName Department DocID 1 Neeraj ENT 101 2 Mohit Ortho 201 3 Ragini ENT 101 4 Mohit Paed. 102 5 Nandini Ortho 201 OPD_Days FEE 100 300 500 290 150 Page 9 of 10 i. Name the fields which can act as primary key and foreign keys for the table Doctors and table Patients. ii. Write the SQL command to update department into OPD if patient name is Neeraj from Patients table. iii. Write the SQL command to display the names of doctors who are in ENT department from table Doctors iv. Write the SQL command to Update the patient name as Raju if FEE is 100 from Patients table. v. Write the SQL command to Delete the Department ENT from Doctors table. 35. A binary file Stock.dat has structure [ItemNo, Item_Name, Company_Name, Cost_Price,Selling_Price]. i. 5 Write a user defined function CreateStockFile() to input data for a record and add ItemNo, Item_Name, Company, Cost_Price and Selling_Price to Stock.dat . ii. Write a function CountRow(Company_Name) in Python which accepts the Company_Name as parameter and count and return number of Items by the given Company that are stored in the binary file Stock.dat OR A binary file EMPLOYEE.DAT has structure (EP_NO, EP_Name, Salary, Phone_No). Write a function countRow() in Python that would read contents of the file EMPLOYEE.DAT and display the details of those employees whose salary is less than 5000. Also display number of employees with salary less than 5000 -END- Page 10 of 10

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