(Where $a _{0}=$ Bohr radius $52.9 pm$ ) is $km s ^{-1}$
(Given : Mass of electron $=9.1 \times 10^{-31} kg$, Planck's constant $h =6.63 \times 10^{-34} \;Js$ )
$\Delta x \times \Delta p _{ x } \geq \frac{ h }{4 \pi}$
$\Rightarrow 2 a _{0} \times m \Delta v _{ r }=\frac{ h }{4 \pi}(\text { minimum })$
$\Rightarrow \Delta v _{ x}=\frac{ h }{4 \pi} \times \frac{1}{2 a _{0}} \times \frac{1}{ m }$
$=\frac{6.63 \times 10^{-34}}{4 \times 3.14 \times 2 \times 52.9 \times 10^{-12} \times 9.1 \times 10^{-31}}$
$=548273\; ms ^{-1}$
$=548.273\; km\;s ^{-1}$
$=548\; km\; s ^{-1}$
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$(i)$ $1s^22s^2p^63s^1$ $(ii)$ $1s^22s^22p^64s^1$
Which of the following statements is/are false ?
$(a)$ Energy is required to change $(i)$ to $(ii)$
$(b)$ $(i)$ represents $‘Na’$ atom
$(c)$ $(i)$ and $(ii)$ represent different elements
$(d)$ More energy is required to remove one electron from $(i)$ than $(ii)$
${N_2}{O_3}\xrightarrow{{R.T.}}NO + N{O_2}$
Assertion $(A)$: Among group $13$ elements, boron's melting point is unusually high $(2453 \mathrm{~K})$.
Reason $(R):$ Solid boron has a strong crystalline lattice.
In the context of the above statements, choose the correct answer from the following options:
$H _{2} F _{2( g )} \rightarrow H _{2( g )}+ F _{2( g )}$
$\Delta U =-59.6\,kJ\,mol ^{-1} \text { at } 27^{\circ}\,C$.
The enthalpy change for the above reaction is (-) $kJ mol ^{-1}$ [nearest integer] Given : $R =8.314\,JK ^{-1}\,mol ^{-1}$