cbse 12th Standard Computer Science Revision of the Basics of Python Important Questions And Answers Study Material - QB365

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Questions:

SECTION-A Multiple Choice Question

All keywords in Python are in _____.

(a)

lower case

(b)

UPPER CASE

(c)

Capitalized

(d)

None of the mentioned

Which of the following is an invalid statement?

(a)

abc = 1,000,000

(b)

a, b, c = 1000,2000,3000

(c)

a,b,c = 1000,2000,3000

(d)

a, b, c = 1000, 2000, 3000

Which of the following is not a complex number?

(a)

k = 2 + 3j

(b)

k = complex(2,3)

(c)

k = 2 + 31

(d)

k = 2 + 3J

Which of these in not a core data type?

(a)

Lists

(b)

Dictionary

(c)

Tuples

(d)

Class

What will be the output of the following code?
x = "abcdef"
i = "i''
while i in x:
print(i, end=" ")

(a)

a b c d e f

(b)

abcdef

(c)

i i i i i...

(d)

No output

Identify the valid declaration of L:
L = [1,23, 'hi', 6]

(a)

list

(b)

dictionary

(c)

array

(d)

tuple

What is the output of "hello" +1+2+3 ?

(a)

hello123

(b)

hello

(c)

Error

(d)

hello6

Each table comprises of _____ and ____

(a)

rows, columns

(b)

data, information

(c)

database, table

(d)

None of these

The design of the database is known as what?

(a)

Attribute

(b)

database scheme

(c)

obstruction

(d)

database oriented

10.

A RDBMS must comply with at least ____ rules.

(a)

(b)

(c)

(d)

11.

Data is a collection of ________ facts which have not been processed to reveal useful information

(a)

Raw

(b)

Facts

(c)

Process

(d)

None of the above

12.

Which of the following properties belong to the database _______________.

(a)

A database is a representation of some aspect of the real world also called miniworld

(b)

It is designed, built and populated with data for specific purposes

(c)

It can be of any size and complexity.

(d)

All of the above

13.

What are the benefits of databases ___________.

(a)

Data Redundancy

(b)

Data Inconsistency

(c)

Lack of Data Integration

(d)

All of the above

14.

Which of the following is not a valid SQL type?

(a)

FLOAT

(b)

NUMERIC

(c)

DECIMAL

(d)

CHARACTER

15.

Which of the following is not a DDL command?

(a)

TRUNCATE

(b)

ALTER

(c)

CREATE

(d)

UPDATE

16.

How many Primary keys can there be in a table?

(a)

Only 1

(b)

Only 2

(c)

Depends on no of Columns

(d)

Depends on DBA

17.

Which of the following is not Constraint in SQL?

(a)

Primary Key

(b)

Not Null

(c)

Check

(d)

Union

18.

Advantages of using DBMS approach

(a)

Reduction in Redundancy

(b)

Improved consistency

(c)

Improved availability

(d)

All of the above

19.

What does an RDBMS consist of?

(a)

Collection of Records

(b)

Collection of Keys

(c)

Collection of Tables

(d)

Collection of Fields

20.

The ability to query data, as well as insert, delete, and alter tuples, is offered by ____________

(a)

TCL (Transaction Control Language)

(b)

DCL (Data Control Language)

(c)

DDL (Data Definition Langauge)

(d)

DML (Data Manipulation Langauge)

21.

Which command is used to remove a relation from an SQL?

(a)

Drop table

(b)

Delete

(c)

Purge

(d)

Remove

SECTION-C (3 Marks)

22.

Explain the two strategies employed by Python for memory allocation.

23.

Write a program to input some numbers repeatedly and print their sum. The program ends when the user says no more to enter (normal termination). The program aborts if a negative number is entered.

24.

Write output of the following codes.
(i) a=8
while (a > 0):
print ("Gotcha!")
a = a-3
if a == 5:
break
else:
print ("Going out!")
(ii) i = 0
while i < 6:
j = 0
while j < i:
print ("*")
j=j+1
i=i+1
print()
(iii) score = 40
while score> 1:
score = (score/2)-1
print (score)

25.

How many times will the given loops iterate.
(i) j=0
while (j < 50):
print ("Hello World")
j=j+1
(ii) j=25
while (25<=j<=30):
print ("Temp variable =",j)
j=j+1
(iii) #Assume Boolean variable b is not known.
b= True
sum=0
while b:
sum=sum+5
print (sum)
if (b or not b):
break

26.

Write a output for SQL queries
(i) to
(ii),which are based on the table: STUDENT given below:

ROLL NO	NAME	CLASS	DOB	GENDER	CITY	MARKS
1	NANDHA	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

(i) SELECT COUNT(*), CIty FROM STUDENT GROUP BY CITY HAVING COUNT(*) >1;
(ii) SELECT MAX(DOB),MIN(DOB) FROM STUDENT
(iii) SELECT NAME,GENDER FROM STUDENT WHERE CITY="Delhi";

27.

Take input of age of 3 people by user and determine oldest and youngest among them.

SECTION-B (2 Marks)

28.

What are Python modules?

29.

Define pow() method.

30.

Explain randrange().

31.

Find and write the output of the following Python
TXT = ["20", "50", "30", "40"]
CNT=3
TOTAL = 0 '"
for C in [7,5,4,6]:
T = TXT[CNT]
TOTAL = float (T) + C
print (TOTAL)
CNT-=1

32.

Find the output from the following code:
t=tuple()
t = t +('Python',)
print (t)
print len(t)
t1=(10,20,30)
print (len(t1))

33.

How many times is the following loop executed?
for a in range(100.10.-10):
print(a)

34.

How many times is the following loop executed?
i = 100
while(i <=200):
print(i)
i + =20

35.

Write a program to print the pyramid.
1
22
333
4444
55555

36.

Find errors in the following codes and write the correct codes. Underline correction in each case.
(i) a = 10
while (a < 100):
print (a)
print ("Over!")
(ii) while x < 10:
print (x)
x = x+2
(iii) for p in range (3)
for q in range (3)
print (p" q)
else:
print ("outer loop ends")

37.

Give a suitable example of a table with sample data and illustrate primary and candidate keys in it.

38.

A table CUSTOMER has 10 columns but no row. Later, 10 new rows are inserted and 3 rows are deleted in the table. What is the degree and cardinality of the table CUSTOMER?

39.

A table STUDENT has 3 columns and 10 rows and another table STUDENT1 has the same number of columns and 15 rows. 5 rows are common in both the tables. If we take union, what is the degree and cardinality of the resultant tabla?

40.

Observe the table CLUB given below:

Member ID	Member Name	Address	Age	Fee
MOODl M0002 M0003 M0004	Sumit Nisha Niharika Sachin	New Delhi Gurgaon New Delhi Faridabad	20 19 21 18	2000 3500 2100 3500

(i) What is the cardinality and degree of the given table?
(ii) If a new column ContactNo has been added and three more members have joined the club then how these changes will affect the degree and cardinality of the table.

41.

What is join in SQL?

SECTION - D (4 Marks Answer is any 4)

42.

Write a program to input n numbers and to search any number from the list.

43.

Write a program to search input any customer name and display customer phone number if the customer name exist in the list.

44.

Given an array: 89,20,31,56,20. Sort this array in ascending order using
i) Bubble Sort (ii) Insertion sort

45.

Write SQL queries for (i) to (iv), which are based on the table: STUDENT

ROLL NO	NAME	CLASS	DOB	GENDER	CITY	MARKS
1	NANDHA	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
8	NISHANTH

(i) To display the records from table STUDENT in alphabetical order as per the name of the student.
(ii) To display Class, DOB and City whose marks is between 450 and 551.
(iii) To display Name, Class and total number of students who have scored more than 450 marks, class wise.
(iv) To increase marks of all students by 20 whose class is "XII".

46.

What is Join? Also, define the different kind of SQL Join.

SECTION-E (5 Marks Answer is any 2)

47.

Write SQL queries for (i) to (iv) and find outputs for SQL queries (v) to (viii),
which are based on the tables.
Table: CUSTOMER

CNO	CNAME	ADDRESS
101	Richa Jain	Delhi
102	Surbhi Sinha	Chennai
103	Lisa Thomas	Bangalore
104	ImranAIi	Delhi
105	Roshan Singh	Chennai

Table: TRANSACTION

TRNO	CNO	AMOUNT	TYPE	DOT
T 001	101	1500	Credit	2017-11-23
T002	103	2000	Dedit	2017-05-12
T003	102	3000	Credit	2017-06-10
T003	103	12000	Credit	2017-09-12
T005	101	1000	Dedit	2017-09-05

(i) To display details of all transactions of TYPE Credit from table TRANSACTION.
(ii) To display the CNO and AMOUNT of all Transactions done in the month of September 2017 from table TRANSACTION.
(iii) To display the last date of transaction (DOT) from the table TRANSACTION for the customer having CNO as 103.
(iv) To display all CNO, CNAME and DOT (date of transaction) of those CUSTOMERS from tables CUSTOMER and TRANSACTION who have done transactions more than or equal to 2000.
(v) SELECT COUNT(*), AVG (AMOUNT) FROM TRANSACTION WHERE DOT> = '2017-06-01';
(vi) SELECT CNO, COUNT("), MAX (AMOUNT) FROM TRANSACTION GROUP BY CNO HAVING COUNT (")> 1;
(vii) SELECT CNO, CNAME FROM CUSTOMER WHERE ADDRESS NOT IN ('DELHI' 'BANGALORE');
(viii) SELECT DISTINCT CNO FROM TRANSACTION;

48.

Write SQL queries for (a) to (g) on the basis of table ITEMS and TRADERS:
Table: ITEMS

CODE	INAME	QTY	PRICE	COMPANY	TCODE
1001 1006 1004 1003 1005	DIGITAL PAD 12i LED SCREEN 40 CAR GPS SYSTEM DIGITAL CAMERA 12X PEN DRIVE 32GB	120 70 50 160 600	11000 38000 21500 8000 1200	XENITA SANTORA GEOKNOW DIGICLICK STOREHOME	T01 T02 T03 T01 T02 T03

TRADERS

TCODE	TNAME	CITY
T01 T02 T03	ELECTRONIC SALES BUSY STORE CROP DISP HOUSE INC	MUMBAI DELHI CHENNAI

(a) To display the details of all the items in ascending order of item names (i.e., INAME).
(b) To display item name and price of all those items, whose price is in the range of 10000 and 22000 (both values inclusive).
(c) To display the number of items, which are traded by each trader. The expected output of this query should be: T01 2 T02 2 T03 1
(d) To display the price, item name and quantity (i.e., qty) of those items which have quantity more than 150.
(e) To display the names of those traders, who are either from DELHI or from MUMBAI.
(f) To display the names of the companies and the names of the items in descending order of company names.
(g) Obtain the outputs of the following SQL queries based on the data given in tables ITEMS and TRADERS above.
(hI) SELECT MAX (PRICE), MIN (PRICE)FROM ITEMS;
(h2) SELECT PRICE"QTY FROM ITEMS WHERE CODE=1004;
(h3) SELECT DISTINCT TCODE FROM ITEMS;
(h4) SELECT INAME, TNAME FROM ITEMS I, TRADERS T
WHERE I.TCODE=T.TCODE AND QTY<100;

49.

Consider the following tables STOCK and DEALERS and answer (a) and (b) parts of this question:
Table: STOCK

ITEM NO	ITEM	DCODE	QTY	UNITPRICE	STOCK DATE
5005 5003 5002 5006 5001 5004 5009		102 102 101 101 102 102 103	100 150 125 200 210 60 160	16 20 14 22 5 10 8	31-03-10 01-01-10 14-02-10 01-01-09 19-03-09 12-12-09 23-01-09

Table: DEALERS

DCODE	DNAME
101 103 102	RELIABLE STATINONERS CLASSIC PLASTICS CLEAR DEALS

(a) Write SQL commands for the following stat~ments :
(i) To display the details of all Items in the STOCK table in ascending order of StockDate.
(ii) To display ltemNo and Item name of those items from STOCK table whose UnitPrice is more than Rupees 10.
(iii) To display the details of those items whose dealer code (Dcode) is 102 or quantity in STOCK (Qty) is more than 100 from the table Stock.
iv) To display maximum UnitPrice of items for each dealer individually as per Dcode from the table STOCK
(b) Give the output of the following SQL queries:
(i) SELECT COUNT(DISTINCT Dcode) FROM STOCK;
(ii) SELECT Qty"' UnitPrice FROM STOCK WHERE ItemNo=5006;
(ill) SELECT Item, Dname FROM STOCK S, DEALERS D WHERE S.Dcode=D.Dcode AND ltemNo =5004;

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Answers Key:

SECTION-A Multiple Choice Question

(d)
None of the mentioned

(b)
a, b, c = 1000,2000,3000

(d)
Class

(d)
No output

(a)
list

(a)
rows, columns

(b)
database scheme

10.

11.

(a)
Raw

12.

(d)
All of the above

13.

(d)
All of the above

14.

(d)
CHARACTER

15.

(d)
UPDATE

16.

(a)
Only 1

17.

(d)
Union

18.

(d)
All of the above

19.

20.

(d)
DML (Data Manipulation Langauge)

21.

(a)
Drop table

SECTION-C (3 Marks)

22.

Python uses two strategies for memory allocation
(i) Reference counting
(ii) Automatic garbage collection
Reference Counting: works by counting the number of times an object is referenced by other in the system. When an object's reference count reaches zero, Python coilects it automatically.
Automatic Garbage Collection: Python schedules garbage collection based upon a threshold of object allocations and object deallocations. When the number of allocations minus the number of deallocations are greater than the threshold number, the garbage collector is run and the unused blocks of memory is reclaimed.

23.

count = sum = 0
ans = 'y'
while ans == 'y':
n = int(input ("Enter a number"))
if n < 0:
print ("Negative number")
break
else:
sum + = n
count + = 1
ans = input("want to enter more number?
(y/n)")
else:
print ("you have entered all your numbers")
print ("Sum of numbers is", sum)

24.

(i) Gotcha!
(ii) *
* *
* * *
* * * *
* * * * *
(iii) 19.0
8.5
3.25

25.

(i) 50 times.
(ii) 6 times
(iii) 1 time

26.

(i) 2 Mumbai
2 Delhi
2 Moscow
(ii) MAX(DOB) MIN(DOB)
07-05-1993
08-12-1995
(iii) NAME GENDER
Sonal F
Store M

27.

print ( "Enter first age" )
first = input ()
print ( "Enter second age" )
second = input ()
print ( "Enter third age")
third = input ()
if first >= second and first >= third
print ( " Oldest is ",first )
elif second >= first and second >= third :
print ( "Oldest is ",second )
elif third >= first and third >= second :
print ( "Oldest is ",third )
else ;
print ( "All are equal " )

SECTION-B (2 Marks)

28.

Modules are Python .py files that consist of Python code. Any Python file can be referenced as a module. Modules can define functions, classes and variables that you can reference in other Python py files via the Python command line interpreter.

29.

pow() method offers to compute the power of a number and hence can make task of calculating power of a number easier. In this, ow types to calculate power.
(i) pow(x, y)
(ii) pow(x, y, mod)

30.

Randrange() method returns a random selected element from the range created by the start, stop and step arguments. The value of start is 0 by default. Similarly, the value of step is 1 by default.

31.

47.0
35.0
54.0
26.0

32.

(Python")
1
3

33.

9 times.

34.

6 times

35.

for i in range(1,6):
for j in range(1,.i+1):
print(i,)
print()

36.

(i) The given loop is infinite loop as the value of a is not changing. There can be lots of possible corrections, one is given below:
a = 10
while (a < 100):
print (a)
a + = 10
print ("Over!")
(ii) The given code is wrong as value of x is not initialized. There can be lots of possible corrections, one is given below:
x=0
while x < 10:
print (x)
x = x+2
(iii) is missing in for statements
for p in range (3):
for q in range (3):
print (p *q)
else:
print ("outer loop ends")

37.

A table may have more than one such attribute/ group of attributes that identifies a row/tuple uniquely, all such attribute(s) are known as candidate keys. Out of the candidate keys, one is selected as primary key.

38.

Degree = 10 (No. of columns)
Cardinality = 10 - 3 = 7 (no. of rows)

39.

Degree: 3
Cardinality: 10 + 15- 5 = 20

40.

(i) Cardinality: 4
Degree: 5
(ii) Cardinality: 7
Degree: 6

41.

SECTION - D (4 Marks Answer is any 4)

42.

n=input("Enter no. of values")
num-[]
flag=0
for i in range(n):
number=input(''Enter the number")
num.append(number)
search = input("Enter number to be searched")
for i in range(n):
if num[i]==search:
print (search, "found at position" ,i)
flag=1
if flag==0:
print (search,"not found in list")

43.

def printlist(s):
i=0
for i in range(len(s)):
print (i,s[i])
i = 0
phonenumbers =['9840012345','9840011111',' 9845622222','9850012345', '9884412345 ']
flag=0
number = raw_input("Enter the phone number to be searched")
number = number.stript)
try:
i = phonenumbers.index(number)
if i >= 0:
flag=1
except ValueError:
pass
if(flag !=0):
print ("\nphone number found i phonebook at index", i)
else:
print ("\nphone number not found ir phonebook")
print (,,\nPHONEBOOK")
printlist(phonenumbers)

44.

i)Bubble Sort
20,89,31,56,20
20,31,89,56,20
20,31,56,20,89
20,31,20,56,89
20,20,31,56,89
(ii)20,89,31,56,20
20,31,89,56,20
20,31,56,89,20
20,31,56,20,89
20,20,31,56,89

45.

(i) SELECT * FROM STUDENT ORDER BYNAME;
(ii) SELECT CLASS,DOB,CITY FROM STUDENT WHERE MARKS BETWEEN 450 AND 551
(iii)SELECT NAME,CLASS ,COUNT(*) FROM STUDENT GROUP BYCLASS HAVING MARKS>450;
(iv) UPDATE STUDENT SETMARKS= MARKS+20 WHERE class="XII";

46.

A join is a query that combines rows from two or more tables. In a join query, more than one tables are listed in FROM clause. The function of combining data from multiple tables is called joining.
Joins are used when we have to select data from two or more tables. Joins are used to extract data from two tables, when we need a relationship between certain columns in these tables There are different kind of SQL joins:
1. Equi-Join:
Equi join is a simple SQL join condition that uses equal sign as a comparison operator.
Syntax
SELECT column 1, column2, column3
FROM Table1,Table2
WHERE Table1. column 1 = Table2.column1;
2. Self Join
A self join is a join where we join a particular table to itself. Here in this case, it is necessary to ensure that the join statement defines an ALIAS name for both the copies of the tables to avoid column ambiquity.
3. Non- Equi join:
Non-equi join is used to return the result from two or more tables, where exact join is not possible. the SQL non - equi join uses comparison operators instead of, the equal sign like >, <, > =, < = alongwith conditions.
Syntax
SELECT*FROM Tablel, Table2
WHERE Tablel. column> Table2.column;
4. Natural Join:
The natural join is a type of equi join and is structured in such a way that, columns with same name of associated tables will appear once only.
Syntax
SELECT*FROM Table1
NATURALJOIN Table2;

SECTION-E (5 Marks Answer is any 2)

47.

(i) SELECT" FROM TRANSACTION WHERE TYPE ="Credit";
(ii) SELECT CNO,AMOUNT FROM TRANSACTION WHERE (MONTH (DOT) = "September" AND YEAR(DOT) =2017);
(iii) SELECT MAX (DOT) FROM TRANSACTION WHERE CNO="103":
(iv) SELECT CNO, CNAME, DOT FROM CUSTOMER.C, TRANSACTION.T
C.CNO=T.CNO AND
AMOUNT> =2000;
(v) 4 4375
(vi) 101 2 1500
103 2 12000
(vii) 102 Surbhi Sinha
105 Roshan Singh
(viii) 101
103
102

48.

(a) SELECT"FROM ITEMSORDER BYINAME ASC;
(b) SELECT INAME, PRICE FROM ITEMS. WHERE PRICE> = 10000 AND PRICE =<22000
(c) SELECT TCODE, COUNT (CODE) FROM ITEMSGROUP BYTCODE;
(d) SELECTPRICE, INAME, QTY FROM 1fEMS WHERE QTY> 150;
(e) SELECTTNAME FROM TRADERS WHERE (CITY = "DELHI") OR (CITY"MUMBAI");
(f) SELECT COMPANY, INAME FROM ITEMS ORDER BYCOMPANYDESC;
(g) (h1) 38000 1200
(h2) 1075000
(h3) T01
T02
T03
(h4)

LED SCREEN 40	DISP HOUSE INC
CAR GPS SYSTEM	ELECTRONICS SALES

49.

(a )(i) SELECT*FROM STOCK ORDER BYStockDate;
(ii) SELECT ItemNo, Item FROM STOCK WHERE UnitPrice> 10;
(iii) SELECT "'FROM DEALERS, STOCK WHERE (DEALERSDcode="102" OR STOCKQty > 100 and DEALERS. DCODE = STOCKDCODE);
(iv) SELECT MAX (UnitPrice) FROM DEALERS, STOCK ORDER BY STOCKDcode WHERE DEALERS.Dcode = STOCK.Dcode;
(b)(i) 3
(ii)4400
(iii)