Class 11 Informatics Practices
Chapter 3 Python Fundamentals
Sumita Arora Book Exercise Solution
Check Points – Question Answer
Check Point 3.1
1. What is meant by token? Name the token available in Python?
Answer: Token is the smallest individual units of a program. It is also called Lexical Unit.
There are five types of tokens: –
(a) Keyword (b) Identifiers (c) Literals
(d) Operators (e) Punctuators
2. What are keywords? Can keywords be used as identifiers?
Answer: Keywords are reserve word of Python programming language. It has special meaning in the program. There are 33 keywords in python.
No keywords cannot be used as Identifiers.
3. What is an identifier? What are the identifier forming rules of Python?
Answer: Identifier is a naming word given by programmer to variable, list, tuples, string, dictionaries, function, class, object, etc. It is known as fundamental building blocks of a program.
Identifier Naming Rules are –
a) Identifier is the combination of alphabets, digits and underscore _
b) Any number of characters you can use.
c) Identifier is a case sensitive, i.e. python is case sensitive language.
d) Identifier only start with either alphabet or digit.
e) A keyword cannot be Identifier.
f) Blank space & special symbols are not allowed in identifier name.
g) Cannot start with digit.
4. Is Python case sensitive? What is meant by the term case sensitive?
Answer: Yes. Python is case sensitive language.
Case sensitive means it treats upper and lower case characters differently.
5. Which of the following are valid identifiers and why / why not?
Data_rec, _data, 1 data, data1, my.file, elif, switch, lambda, break?
Data_rec : This is a valid identifier.
_data : This is a valid identifier.
1 data : This is NOT VALID identifier, because It start with digit and having space also.
Data1 : This is a valid identifier.
my.file : This is NOT VALID identifier, because . (dot) is a special symbol, which not allowed. Only underscore _ is allowed.
elif : This is NOT VALID identifier, because elif is a keyword.
switch : This is a valid identifier.
lambda : This is NOT VALID identifier, because lambda is a keyword.
break : This is NOT VALID identifier, because break is a keyword.