PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
A developer writes the following code: x = 5; y = x; x = 10. What are the values of x and y after execution?
⚠ Common exam trap
Python Institute often tests the misconception that `y = x` creates a persistent link between variables, leading candidates to incorrectly assume `y` changes when `x` is reassigned.
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
✓
x = 10, y = 5
In Python, integers are immutable, and the assignment `y = x` copies the reference to the integer object 5, not the variable itself. When `x = 10` is executed, it binds the name `x` to a new integer object 10, while `y` still references the original object 5. Thus, after execution, `x` is 10 and `y` is 5.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
x = 10, y = 5
Why this is correct
Assignment binds the name y to the integer object 5, not to the variable x. Rebinding x to 10 therefore leaves y untouched, so x = 10 and y = 5. This satisfies the stem's constraint that integers are immutable and assignment copies the reference, not a live link.
- ✗
x = 5, y = 10
Why it's wrong here
Assignment copies the value 5 into y, and rebinding x to 10 afterwards leaves y untouched at 5. The reversed pairing swaps the variables, which would only occur if the second statement assigned x into y after the rebinding, not before it.
- ✗
x = 5, y = 5
Why it's wrong here
Rebinding x to 10 after y = x leaves y holding the original 5, so x cannot remain 5. This pairing reflects the mistaken belief that reassigning x also updates y, confusing Python's independent name binding with a shared reference.
- ✗
x = 10, y = 10
Why it's wrong here
y = x copies the value 5 into y at that moment; later rebinding x to 10 does not propagate to y. This pairing would hold only if both names referenced one shared mutable object whose contents changed, which integers do not.
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