PCEP Computer Programming and Python Fundamentals Practice Question

A programmer is debugging a Python script that uses a while loop to process a list of numbers. The code is:

numbers = [1, 2, 3, 4, 5] i = 0

while i < len(numbers):
    if numbers[i] % 2 == 0:
        print(numbers[i])

i += 1

What is the output of this code?

⚠ Common exam trap

The trap here is misreading the modulo condition and thinking it prints odd numbers, or overlooking the increment that prevents an infinite loop.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

2 4

The while loop iterates through the list by index, checking each element for evenness using the modulo operator. When an even number is found, it is printed. The loop correctly increments the index, so it terminates after processing all elements. The even numbers in the list are 2 and 4, so they are printed on separate lines.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
2 4 6
Why it's wrong here
The list only contains numbers up to 5, so 6 is not in the list and cannot be printed. The loop iterates over the given list, and the condition only checks elements present. There is no 6, so it is not output. This option mistakenly assumes the loop generates numbers beyond the list.
✗
An infinite loop occurs because i is not incremented.
Why it's wrong here
The variable i is incremented by 1 at the end of each iteration (i += 1). This ensures the loop progresses and terminates when i reaches len(numbers), which is 5. There is no infinite loop. This option incorrectly claims that the increment is missing, but it is present in the code.
✗
1 3 5
Why it's wrong here
This would be the output if the condition were numbers[i] % 2 != 0, which checks for odd numbers. The code checks for even numbers, so it prints evens, not odds. The numbers 1, 3, and 5 are odd and do not satisfy the condition. Therefore, they are not printed. This option confuses the modulo condition.
✓
2 4
Why this is correct
The loop iterates over the list using index i from 0 to 4. The condition checks if the current number is even (numbers[i] % 2 == 0). For 1, it's odd (no print). For 2, it's even (print 2). For 3, odd. For 4, even (print 4). For 5, odd. So the output is 2 and 4 on separate lines. The loop increments i correctly, avoiding an infinite loop.

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PCEP Computer Programming and Python Fundamentals Practice Question

Why each option matters

Option-by-option breakdown

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