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

$A$: Thomson's atomic model is known as the plum pudding model.
$R$: The atom is considered as a positively charged sphere in which electrons are embedded.

At what condition is the energy of an electron in an atom considered to be zero?

Bohr's radius can have

In astronomical observations,signals observed from the distant stars are generally weak. If the photon detector receives a total of $3.15 \times 10^{-18} \, J$ from the radiations of $600 \, nm$,calculate the number of photons received by the detector.

When an electron moves from $L$-shell to $M$-shell,then it will be accompanied by :