Identity operators (is, is not) in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of identity comparison with small integers

What is the output of this code snippet?

Python

a = 256
b = 256
print(a is b)

A True

B False

C SyntaxError

D TypeError

💡 Hint

Small integers are cached by Python, so identical values share the same object.

Python caches small integers from -5 to 256, so variables with the same value in this range point to the same object, making 'is' return True.

❓ Predict Output

intermediate

Identity comparison with lists

What is the output of this code?

Python

list1 = [1, 2, 3]
list2 = [1, 2, 3]
print(list1 is list2)

A True

B False

C SyntaxError

D TypeError

💡 Hint

Two lists with the same content are different objects in memory.

Even if two lists have the same content, they are different objects, so 'is' returns False.

🧠 Conceptual

advanced

Understanding 'is not' with None

Which option correctly checks if variable x is not None?

A if x not None:

B if x != None:

C if x is not None:

D if x is None:

💡 Hint

Use identity operators to check against None.

The correct way to check if x is not None is using 'is not None'. Using '!=' works but is not recommended for identity checks.

❓ Predict Output

advanced

Output of identity comparison with strings

What is the output of this code?

Python

s1 = 'hello world'
s2 = 'hello world'
print(s1 is s2)

A False

B SyntaxError

C True

D TypeError

💡 Hint

Strings with spaces may not be interned automatically.

Python may not intern strings with spaces automatically, so s1 and s2 are different objects, making 'is' return False.

🔧 Debug

expert

Identify the error in identity operator usage

Which option will cause a SyntaxError when using identity operators?

A if a is not b:

B if a is not None:

C if a is b:

D if a is! b:

💡 Hint

Check the correct syntax for 'is not' operator.

'is not' is two separate words. 'is!' is invalid syntax and causes SyntaxError.