The diagram below shows the lowest four energy levels for an electron in a hypothetical atom.The electron is excited to the $-1\,eV$ level of the atom and transitions to the lowest energy state by emitting only two photons. Which of the following energies could not belong to either of the photons ? .....$eV$
$2$
$4$
$5$
$6$
In 1911 , the physicist Ernest Rutherford discovered that atoms have a tiny, dense nucleus by shooting positively charged particles at a very thin gold foil. A key physical property which led Rutherford to use gold was that it was
The first line in the Lyman series has wavelength $\lambda $ . The wavlength of the first line in Balmer series is
What is the atomic number of gold ?
Orbital acceleration of electron is
Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is