The threshold frequency for a photosensitive metal is 3.3 $$ \times $$ 10¹⁴ Hz. If light of frequency 8.2 $$ \times $$ 10¹⁴ Hz is incident on this metal, the cut- off voltage for the photoelectron emission is nearly

An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function 2.75 eV. If the stopping potential of the photoelectron is 10 V, then the value of n is

Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0. number of P species are 4 N₀ and that of Q are N₀. Half -life of P (for conversion to R) is 1 minute where as that of Q is 2 minutes. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be

Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model?