Which one is the wrong statement?

de-Broglie's wavelength is given by $\displaystyle \lambda=\frac{\mathrm{h}}{\mathrm{m} v}$, where $\displaystyle \mathrm{m}=$ mass of the particle, $\displaystyle v=$ group velocity of the particle.

The uncertainty principle is $\displaystyle \Delta \mathrm{E} \times \Delta \mathrm{t} \geqslant \mathrm{h} / 4 \pi$.

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.