O Level Python Paper January 2021

1. The variable a is assigned a string value “Meetmeatafterparty”, but it is not enclosed in quotes. This will result in a syntax error.
2. The variable b is assigned an integer value 13.

Correct Answer: C) error in code

• The __init__ method takes a parameter id, and assigns that value to the instance attribute self.id.
• The line id = 555 modifies the local id variable in the constructor, but does not affect the instance variable self.id.
• When you print acc.id, it will print the value that was passed into the constructor, which is 111.

Output:

Explanation:

• The id inside the __init__ method is a local variable. Changing it doesn't affect the instance variable self.id.
• So, the value of self.id remains as 111 even though id = 555 is set within the constructor.self.id = id इंस्टेंस वेरिएबल को असाइन करता है। अगली लाइन id = 555 केवल एक लोकल वेरिएबल को बदलती है, क्लास के
• self.id को नहीं। इसलिए acc.id का मान 111 ही रहेगा।

Correct Answer: A) 111

The invalid variable in the list is:

(D) 1st_string

In most programming languages, variable names cannot start with a number. So, 1st_string is an invalid variable name because it starts with a digit (1).

The other options are valid variable names:

• (A) my_string_1: This is valid.
• (B) foo: This is valid.
• (C) __: This is valid, though it's often used for special purposes in some languages (like Python). 

• • पायथन में वेरिएबल का नाम कभी भी अंक (digit) से शुरू नहीं हो सकता।

Correct Answer: D) 1st_string

• The upper() method: The upper() method returns a new string with all characters in uppercase. However, strings in Python are immutable, meaning that calling upper() on a string does not modify the original string in place. Instead, it returns a new string. In the loop, the result of i.upper() is not assigned to any variable or used, so it has no effect on the original list x.

• The loop: The loop iterates through each string in the list x. For each string, i.upper() is called, but since the result is not used, the strings in the list x remain unchanged.

• Printing the list x: After the loop finishes, the list x remains as ['ab', 'cd'] because no modifications have been made to it.

• स्ट्रिंग के मेथड जैसे upper() मूल स्ट्रिंग को नहीं बदलते (क्योंकि स्ट्रिंग Immutable होती है)। जब तक आप i = i.upper() नहीं करते और उसे वापस लिस्ट में नहीं डालते, लिस्ट वैसी ही रहेगी।

Correct Answer: C) ['ab','cd']

The given program formats the string using the format() method:

• {0:4f}: Formats a (which is 2) as a float with 4 decimal places → 2.0000
• {0:3d}: Formats a (which is 2) as an integer with a width of 3 → 2
• {2}: Prints c (which is -8)
• {1}: Prints b (which is '3.77')

So, the output is:

(A) 2.0000 2 -8 3.77

{0:4f} संख्या को फ्लोट में बदलता है (डिफ़ॉल्ट 6 डेसिमल), {0:3d} उसे इंटीजर की तरह स्पेस के साथ दिखाता है। (नोट: प्रश्न के विकल्पों में डेसिमल की संख्या में अंतर हो सकता है, लेकिन तर्क यही है)।

Correct Answer: A) 2.0000 2 -8 3.77

Let's analyze the given Python code step by step:

def gfg(x, l=[]):
    for i in range(x):
        l.append(i * i)
    print(l)

gfg(2)

1. Function gfg:

   • It takes two parameters: x and l. l has a default value of an empty list [].
   • Inside the function, a loop runs from 0 to x-1 (inclusive). In each iteration, it appends i*i (the square of i) to the list l.

2. Calling gfg(2):

   • x = 2 and l uses the default value [] (an empty list).
   • The loop will run for i = 0 and i = 1:
     • When i = 0: 0*0 = 0, so 0 is appended to the list.
     • When i = 1: 1*1 = 1, so 1 is appended to the list.

3. Final result: After the loop, the list l will contain [0, 1] and that will be printed.

Output:

(B) [0, 1]

Explanation:

• Since the list l starts empty and the loop runs twice (for i = 0 and i = 1), the final list becomes [0, 1].

• • range(2) का मतलब है 0 और 1। i*i करने पर 0*0=0 और 1*1=1 लिस्ट में जुड़ेंगे।

Correct Answer: B) [0, 1]

Let's break down the options for the given tuple t = (1, 2, 4, 3):

• (A) print(t[3]): This is correct. Indexing starts from 0, so t[3] refers to the fourth element, which is 3. This will print 3.

• (B) t[3] = 45: This is incorrect. Tuples are immutable in Python, meaning their elements cannot be changed after creation. Attempting to modify t[3] will result in a TypeError.

• (C) print(max(t)): This is correct. The max() function returns the largest element in the tuple. Here, the largest element is 4, so it will print 4.

• (D) print(len(t)): This is correct. The len() function returns the number of elements in the tuple. Here, the length of t is 4, so it will print 4.

Answer:

The incorrect statement is:

(B) t[3] = 45

टपल (Tuple) Immutable होते हैं, यानी एक बार बनने के बाद उनके तत्वों को बदला नहीं जा सकता।

Correct Answer: B) t[3]=45

The given Python code is:

t1 = (1, 2, 4, 3)
t2 = (1, 2, 3, 4)
print(t1 < t2)

Step-by-Step Explanation:

• Tuples in Python are ordered, immutable collections of elements.
• When comparing two tuples, Python compares them element by element from left to right.
• If the first elements are equal, it moves to the next element and so on.
• If one tuple is smaller than the other at any point, the comparison is decided based on that element.

Now, let's compare t1 and t2:

• t1 = (1, 2, 4, 3)
• t2 = (1, 2, 3, 4)

Comparing element by element:

1. The first elements (1 in both t1 and t2) are equal, so we move to the next element.
2. The second elements (2 in both t1 and t2) are also equal, so we move to the next element.
3. The third elements are different: t1 has 4, while t2 has 3.
   • Since 4 > 3, t1 is not less than t2.

Therefore, the result of the comparison t1 < t2 is False.

Answer:

(B) False

पायथन टपल्स की तुलना पहले तत्व से शुरू करता है। यहाँ $1=1$ और $2=2$ है, लेकिन तीसरे स्थान पर $4 < 3$ गलत है, इसलिए परिणाम False आएगा।

Correct Answer: B) False

यह गलत है। एक रिकर्सिव फ़ंक्शन बिना कुछ रिटर्न किए भी प्रिंट जैसा कार्य कर सकता है (जैसे ट्री ट्रैवर्सल)। हालाँकि, बेस केस होना अनिवार्य है।

Correct Answer: D) Every recursive function must have a return value (प्रत्येक पुनरावर्ती फ़ंक्शन का एक रिटर्न मान होना चाहिए)

The code uses functools.reduce() to find the largest number in the list l = [1, 2, 3, 4, 5].

• The lambda x, y: x if x > y else y function compares two numbers at a time and keeps the larger one.
• After comparing all elements, the largest number 5 is stored in m.

Output:

(D) 5reduce फ़ंक्शन यहाँ दी गई लिस्ट में सबसे बड़ी संख्या (Max) ढूँढ रहा है।

Correct Answer: D) 5

Let's break down the given Python code step by step:

r = lambda q: q * 2
s = lambda q: q * 3
x = 2
x = r(x)
x = s(x)
x = r(x)
print(x)

Step-by-Step Explanation:

1. Define the lambdas:

   • r = lambda q: q * 2: This lambda function doubles the input.
   • s = lambda q: q * 3: This lambda function triples the input.

2. Initial value of x:

   • x = 2

3. Apply r(x):

   • x = r(x) means x = 2 * 2 = 4. Now, x is 4.

4. Apply s(x):

   • x = s(x) means x = 4 * 3 = 12. Now, x is 12.

5. Apply r(x) again:

   • x = r(x) means x = 12 * 2 = 24. Now, x is 24.

6. Final output:

   • print(x) prints the final value of x, which is 24.

Answer:

(B) 24

$x=2 \rightarrow r(2)=4 \rightarrow s(4)=12 \rightarrow r(12)=24$.

Correct Answer: B) 24

Let's analyze the given Python code:

a = True
b = False
c = False
if a or b and c:
    print("TRUE")
else:
    print("FALSE")

Step-by-Step Explanation:

1. Variables:

   • a = True
   • b = False
   • c = False

2. Condition in the if statement:

   • The expression a or b and c involves both the logical or and and operators.
   • Operator Precedence: In Python, and has higher precedence than or. So, b and c is evaluated first.

3. Evaluate b and c:

   • b and c evaluates as False and False, which is False.

4. Evaluate a or (b and c):

   • Now the condition becomes a or False, which is True or False, which is True.

5. Result:

   • Since the condition evaluates to True, the code inside the if block is executed, so "TRUE" is printed.

Answer:

(A) TRUE

if a or b and c में or की वजह से यदि a (True) है, तो पूरा एक्सप्रेशन True हो जाता है।

Correct Answer: A) TRUE

• • रिकर्शन 'Stack' का उपयोग करता है, इसलिए यह अधिक मेमोरी लेता है।

Correct Answer: A) MORE

टपल () का उपयोग करते हैं।

Correct Answer: B) parentheses