The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is $.... \times 10^{-19} \, J$
[Given: The threshold frequency of platinum is $1.3 \times 10^{15} \, s^{-1}$ and $h = 6.6 \times 10^{-34} \, J \, s$.]

Which of the following transitions has the minimum wavelength?

Which one of the following statements is not correct?

The ionization energy of a $H$ atom is $13.6 \, eV$. The energy required to excite the electron from the ground state $(n=1)$ to the first excited state $(n=2)$ is ... $eV$.

Which orbit of $Be^{+3}$ has the same orbit radius as that of the ground state of hydrogen atom?

Energy levels $A, B, C$ of a certain atom correspond to increasing values of energy,$i.e.,$ $E_A < E_B < E_C$. If $\lambda_1, \lambda_2$ and $\lambda_3$ are the wavelengths of radiations corresponding to the transitions $C$ to $B$,$B$ to $A$ and $C$ to $A$ respectively,which of the following statements is correct?