Some questions are asked by class 11 students related to Computer Science (Python)

Question 1:
What is the difference between a keyword and an identifier ?
Answer:
Keyword is a special word that has a special meaning and purpose. Keywords are reserved and are few. For example : if, else, elif etc.
Identifier is the user-defined name given to a part of a program like variable, object, functions etc. Identifiers are not reserverd. These are defined by the user but they can have letters, digits and a symbols underscore. They must begin with either a letter or underscore. For example : chess, _ch, etc.

Question 2:
What are literals in Python ? How many types of literals are allowed in Python ?
Answer:
Literals mean constants i.e. the data items that never change value during a program run. Python allow five types of literals :

1. String literals
2. Numeric literals
3. Boolean literals
4. Special literal (None)
5. Literal collections like tuples, lists etc.

Question 3:
How many ways are there in Python to represent an integer literal ?
Answer:
Python allows three types of integer literals :

1. Decimal (base 10) integer literals.
2. Octal (base 8) integer literals.
3. Hexadecimal (base 16) integer literals.
   For example, decimal 12 will be written as 14 as octal integer and as OXC as hexa decimal integer. (12)10 = (14)8 = (OXC)16. (as hexa decimal)

Question 4:
How many types of strings are supported in Python ?
Answer:
Python allows two string types :

1. Single line strings : Strings that are terminated in single line. For example :
   str = ‘Oswal Books’
2. Multiple strings : Strings storing multiple lines of text. For example :
   str = ‘Owal \
   Books’
   or str = ” ” ” Oswal
   Books
   ” ” “

Question 5:
What is “None” literal in Python ?
Answer:
Python has one special literal called ‘None’. The ‘None’ literal is used to indicate something that has not yet been created. It is also used to indicate the end of lists in Python.

Question 6:
What factors guide the choice of identifiers in Programs ?
Answer:

1. An identifier must start with a letter or underscore followed by any number of digits or/ and letters.
2. No special character (other than under-score) should be included in the identifier.
3. No reserved word or standard identifier should be used.
4. Upper and lower case letters are different. All characters are significant.

Question 7:
What will be the size of the following constants : “\a”. “\a”, “Manoj\’s”, ‘\”, “XY\ YZ”
Answer:
‘\a’ – size is 1 as there is one character and it is a string literal enclosed in single quotes.
“\a” – size is 1 as there is one character enclosed in double quotes.
“Manoj\’s” – size is 7 because it is a string having 7 characters enclosed in double quotes.
“\” – size is 1. It is a character constant and is containing just one character \”.
“XY\ – size is 4. It is a multiline string create YZ” with \ in the basic string.

Question 8:
What is the difference between a tuple and a list ?
Answer:
A tuple is immutable i.e. cannot be changed. It can be operated on only. But a list is mutable. Changes can
be done internally to it.
tuple initialization: a = (2,4,5) list initialization: a = [2,4,5]

Question 9:
Write various python modules convert the list to generate the output “one, two, three” ? a = [‘one’, ‘two’, ‘three’]
Answer:
> > > a = [‘one’,’two’,’three’]
>>> ‘,’.join(a)
‘one,two,three’

Question 10:
What would the following code yield ? word = ‘abcdefghij’
Answer:abcdefghij
print word[:3] + word[3:]

Question 11:
Is there a tool to help find bugs or perform static analysis?
Answer:
Yes. PyChecker is a static analysis tool that finds bugs in Python source code and warns about code complexity and style. Pylint is another tool that checks if a module satisfies a coding standard, and also makes it possible to write plug-ins to add a custom feature.

Question 12:
What is a tuple ?
Answer:
A tuple is another sequence data type that is similar to the list. A tuple consists of a number of values separated by commas. Unlike lists, however, tuples are enclosed within parentheses.

Question 13:
What is a list?
Answer:
Lists are the most versatile of Python’s compound data types. A list contains items separated by commas and enclosed within square brackets ([ ]). To some extent, lists are similar to arrays in C. One difference between them is that all the items belonging to a list can be of different data type.

Question 14:
Explain String data type.
Answer:
Strings in Python are identified as a contiguous set of characters in between quotation marks. Python allows for either pairs of single or double quotes. Subsets of strings can be taken using the slice operator ( [ ] and [ : ] ) with indexes starting at 0 in the beginning of the string and working their way from -1 at the end.

Question 15:
What is a Number data types ?
Answer:
Number data types store numeric values. They are immutable data types, which means that changing the value of a number data type results in a newly allocated object.

Question 16:
Write the names of all Standard Data Types.
Answer:
(a) Numbers
(b) String
(c) List
(d) Tuple
(e) Dictionary

Question 17:
Write a list comprehension that builds a list of the even numbers from 1 to 10 (inclusive).
Answer:
foo = [x for x in range(l, 11) if (x % 2) = = 0] print foo [2,4,6,8,10]

Question 18:
When do you use list vs. tuple vs. dictionary vs. set?
Answer:
‘List’ is like an array, individual element of list data can be accessed using indexing and can be manipulated. “Tuples” are similar to list, but there data can be changed once created through the execution of program. ‘Set’ stores unordered values and have no index. And unlike Tuples and lists, sets can have no duplicate data. “Dictionary” is similar to what their name is. It consist of pairs of keys and thier corresponding values.

Question 19:
Explain the dictionary in Python.
Answer:

• Python’s built-in data type is dictionary, which defines one-to-one relationships between keys and values.
• Dictionary is indexed by keys.
• Dictionary is similar to association array or hash table of other languages.
• Dictionary consist of pairs’-of keys and their corresponding values.

Question 20:
What is PEP 8?
Answer:
PEP 8 is a coding convention(a set of recommendations) to write your Python code in order to make it more readable and useful for those after you.

Question 21:
Explain how Python is interpreted.
Answer:
Python program runs directly from the source code. Each type Python programs executed code is required. Python converts source code written by the programmer into intermediate language which is again translated into the native language/ machine language that is executed. So Python is an interpreted language.