A hydrogen atom in its first excited state absorbs a photon of energy x $$\times$$ 10^{$$-$$2} eV and excited to a higher energy state where the potential energy of electron is $$-$$1.08 eV. The value of x is ______________.

The half life of a radioactive substance is 5 years. After x years a given sample of the radioactive substance gets reduced to 6.25% of its initial value. The value of x is ____________.

$$\sqrt {{d_1}} $$ and $$\sqrt {{d_2}} $$ are the impact parameters corresponding to scattering angles 60$$^\circ$$ and 90$$^\circ$$ respectively, when an $$\alpha$$ particle is approaching a gold nucleus. For d_{1} = x d_{2}, the value of x will be ____________.

A beam of monochromatic light is used to excite the electron in Li^{+ +} from the first orbit to the third orbit. The wavelength of monochromatic light is found to be x $$\times$$ 10^{$$-$$10} m. The value of x is ___________.

[Given hc = 1242 eV nm]