Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYMedium

Which one is the wrong statement?

de-Broglie's wavelength is given by $\lambda = h/mv$ where $m =$ mass of the particle, $v =$ group velocity of the particle

The uncertainty principle is $\Delta E \cdot \Delta t \ge h/4\pi$

Half-filled and fully filled orbitals have greater stability due to greater exchange energy, greater symmetry and more balanced arrangement

The energy of 2s-orbital is less than the energy of 2p-orbital in case of hydrogen like atoms

We analyze each statement:

de-Broglie Wavelength: The equation $\lambda = h/mv$ correctly represents the wavelength of a matter wave. This is a correct statement.
Uncertainty Principle: Heisenberg's uncertainty principle can be expressed in terms of energy and time as $\Delta E \Delta t \ge \frac{h}{4\pi}$ . This is a correct statement.
Orbital Stability: As seen in transition elements (Source: Chemistry Class 12, Unit 4, Section 4.3.3), half-filled and fully filled orbitals exhibit extra stability due to high exchange energy and symmetrical distribution of electrons. This is a correct statement.
Energy Levels in Hydrogen: For hydrogen-like atoms (single-electron systems), the energy of an orbital depends only on the principal quantum number ( $n$ ). Therefore, the energy of the 2s orbital is equal to the energy of the 2p orbital ( $E_{2s} = E_{2p}$ ). The statement that $2s < 2p$ is true only for multi-electron atoms where shielding effects occur. Thus, this is the wrong statement.

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