Heisenberg Uncertainty Principle Statements | JEE Mains PYQ | Structure of Atom
Q. Given below are two statements :

Statement (I): It is impossible to specify simultaneously with arbitrary precision, both the linear momentum and the position of a particle.

Statement (II): If the uncertainty in the measurement of position and uncertainty in measurement of momentum are equal for an electron, then the uncertainty in the measurement of velocity is
≥ √( h / π ) × 1 / (2m).

In the light of the above statements, choose the correct answer:

A. Both Statement I and Statement II are true
B. Both Statement I and Statement II are false
C. Statement I is true but Statement II is false
D. Statement I is false but Statement II is true
Explanation
Step 1: Analyze Statement I

This is a direct statement of Heisenberg Uncertainty Principle:
Δx · Δp ≥ h / 4π
Hence, position and momentum cannot be measured simultaneously with arbitrary precision.
✔ Statement I is true.

Step 2: Analyze Statement II

Given: Δx = Δp

Using uncertainty relation:
Δx · Δp ≥ h / 4π
(Δp)² ≥ h / 4π
Δp ≥ √( h / 4π )

Since momentum p = mv,
Δp = m Δv
⇒ Δv ≥ √( h / 4π ) / m

Which can be written as:
Δv ≥ √( h / π ) × 1 / (2m)
✔ Statement II is true.

Correct Answer = Both Statement I and Statement II are true

Updated for JEE Main 2026: This PYQ is important for JEE Mains, JEE Advanced and other competitive exams. Practice more questions from this chapter.

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