CBSE Class 12 Computer Science Revision Of The Basics Of Python Assignment

Short Answer Type Questions :

Question: What is None literal in Python?
Answer: Python has one special literal called “None”. It is used to indicate something that has not yet been created. It is a legal empty value in Python.

Question: Can List be used as keys of a dictionary?
Answer: No, List can’t be used as keys of dictionary because they are mutable. And a python dictionary can have only keys of immutable types.

Question: Rewrite the code after correcting errors: –
if N=>0
print(odd)
else
Print(“even”)
Answer: – if N>=0:
print(“odd”)
else:
print(“even”)

Question: What is a python variable? Identify the variables that are invalid and state the reason Class, do, while, 4d, a+
Answer: – A variable in python is a container to store data values.
a) do, while are invalid because they are python keyword
b) 4d is invalid because the name can’t be started with a digit.
c) a+ is also not validas no special symbol can be used in name except underscore ( _ ).

Question: Predict the output
for i in range( 1, 10, 3):
print(i)
Answer: – 1
4
7

Question: What will be the output of the following code snippet?
values =[ ]
for i in range (1,4):
values.append(i)
print(values)
Answer: [1]
[1 ,2 ]
[1,2,3]

Question: What problem occurs with the following code
X=40
while X< 50 :
print(X)
Answer: – The given code does not have the incrementing value of X, thus the loop becomes endless.

Question: Find the error in following code. State the reason of the error.
aLst = { ‘a’:1 ,’ b’:2, ‘c’:3 }
print (aLst[‘a’,’b’])
Answer: The above code will produce KeyError, the reason being that there is no key same as the list [‘a’,’b’] in dictionary aLst.

Application Based Questions :

Question: Find output of the following code fragment.
x=”hello world”
print(x[:2],x[:-2],x[-2:])
print(x[6],x[2:4])
print(x[2:-3],x[-4:-2])
Answer: he hello wor ld
w ll
llo wo or

Question: Rewrite the following programs after removing syntactical errors:
for=20
for1=50:
for3=for+for1+for2
print(for3)
Answer: f=20 #( as for is a keyword in python)
for1=50 #(: can not be used here)
for3=f+for1 #(for2 not defined)
print(for3)