Q45 / 180 · NEET 2017 · Chemistry

Which one of the following statements is wrong?

A
de-Broglie's wavelength is given by $λ = \frac{h}{mv}$ , were $m =$ mass of the particle, $v =$ group velocity of the particle.
B
The uncertainty principle is $ΔE \times Δt \geq \frac{h}{4 π}$ .
C
Half-filled and fully-filled orbitals have greater stability due to the greater exchange energy, greater symmetry and more balanced arrangement.
Correct answer
D
The energy of $2 s$ orbital is less than the energy of $2 p$ orbital in case of hydrogen-like atoms.

Solution

(i)

λ = \frac{h}{p} = \frac{h}{mv}

(ii)

Δx . Δp = \frac{h}{4 π}

Δx \times \frac{Δp \times dt}{Δt} \geq \frac{h}{4 π}

∴ \frac{Δp}{Δt} = f

fΔx Δt \geq \frac{h}{4 π}

fΔx = ΔE

ΔE . Δt \geq \frac{h}{4 π}

(iii)

3^{rd}

statement is true.

(iv) The energy of

2 s -

orbital and

2 p -

orbital in case of hydrogen like atoms is equal because they are single electron species.

Hence, the correct answer is option: 'D'.