The output of the given combination gates represents :

Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?

An electron of mass m and a photon have same energy E. The ratio of wavelength of electron to that of photon is : (c being the velocity of light)

The radius in kilometer to which the present radius of earth (R = 6400 km) to be compressed so that the escape velocity is increased 10 times is ___________.