Heisenberg's uncertainty principle states
A{'text': 'ΔE × Δt = h always', 'label': 'A'}
B{'text': 'Δx × Δp = 0 for microscopic particles', 'label': 'B'}
C{'text': 'Δx × Δp ≥ h/(2π), sometimes written as h/4π', 'label': 'C'}
D{'text': 'Δx and Δp can be measured with arbitrary precision', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': 'Δx × Δp ≥ h/(2π), sometimes written as h/4π', 'label': 'C'}
1. Simultaneous precise measurement of conjugate variables is impossible.
2. For position and momentum: Δx × Δp ≥ h/(4π) (equivalently ℏ/2).
3. The more precisely x is known, the less precisely p can be, and vice versa.
4. This is a fundamental limit, not an instrumental error.
_Source: NCERT Class 11 Chemistry, Ch 2 "Structure of Atom", §2.6_
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