The ratio of the difference in energy between the first and second Bohr orbits to that between the second and third orbits is

$1$ mole of photons,each of frequency $2500 \ s^{-1}$,would have approximately a total energy of:

Which one of the following is considered as the main postulate of Bohr’s model of atom?

For a hydrogen atom,the energy of the $n^{th}$ orbit is given by the equation $E \propto n^y$. What is the value of $y$?

The following figure shows the spectrum of an ideal black body at four different temperatures. The number of correct statement$(s)$ from the following is $..............$.
$A$. $T_4 > T_3 > T_2 > T_1$
$B$. The black body consists of particles performing simple harmonic motion.
$C$. The peak of the spectrum shifts to shorter wavelength as temperature increases.
$D$. $\frac{T_1}{v_1} = \frac{T_2}{v_2} = \frac{T_3}{v_3} \neq \text{constant}$
$E$. The given spectrum could be explained using quantization of energy.

If the radius of the electron orbit in the excited state of a hydrogen atom is $476.1 \ pm$, the energy of the electron in that excited state in $J$ is (Radius and energy of the electron in the first orbit of a hydrogen atom are $52.9 \ pm$ and $-2.18 \times 10^{-18} \ J$ respectively).