A metal surface is exposed to $500 \mathrm{nm}$ radiation. The threshold frequency of the metal for photoelectric current is $4.3\times {10}^{14} \mathrm{Hz}$. The velocity of ejected electron is $\_\_\_\times {10}^5{ \mathrm{ms}}^{-1}$ (Nearest integer)
$\left[\mathrm{Use}:\mathrm{h}=6.63\times {10}^{-34}\mathrm{Js}, {\mathrm{m}}_{\mathrm{e}}=9.0\times {10}^{-31} \mathrm{kg}\right]$

Given below are two statements :
Statement I : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in positive charges on the nucleus as there is no strong hold on the electron by the nucleus.
Statement II : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in principle quantum number.

In the light of the above statements, choose the most appropriate answer from the options given below:

An accelerated electron has a speed of $5\times {10}^6{ \mathrm{ms}}^{-1}$ with an uncertainty of $0.02\%$. The uncertainty in finding its location while in motion is $x\times {10}^{-9} \mathrm{m}$.
The value of $x$ is __________. (Nearest integer)

[Use mass of electron$=9.1\times {10}^{-31} \mathrm{kg}$,

$\left.\mathrm{h}=6.63\times {10}^{-34}\mathrm{Js},\mathrm{\pi }=3.14\right]$

A source of monochromatic radiation wavelength $400 \mathrm{nm}$ provides $1000 \mathrm{J}$ of energy in $10$ seconds. When this radiation falls on the surface of sodium, $\mathrm{x}\times {10}^{20}$ electrons are ejected per second. Assume that wavelength $400 \mathrm{nm}$ is sufficient for ejection of electron from the surface of sodium metal. The value of $\mathrm{x}$ is ______. (Nearest integer)

$\left(\mathrm{h}=6.626\times {10}^{-34} \mathrm{Js}\right)$

The correct plot for $3\mathrm{s}$ orbital is :

According to Bohr's atomic theory:
(A) Kinetic energy of electron is $\propto \frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}.$
(B) The product of velocity (v) of electron and principal quantum number $\left(\mathrm{n}\right), \text{'}vn\text{'}\propto {\mathrm{Z}}^2.$
(C) Frequency of revolution of electron in an orbit is $\propto \frac{{\mathrm{Z}}^3}{{\mathrm{n}}^3}.$
(D) Coulombic force of attraction on the electron is $\propto \frac{{\mathrm{Z}}^3}{{\mathrm{n}}^4}.$

Choose the most appropriate answer from the options given below: