Two radiations of photons energies \(1\) eV and \(2.5\) eV, successively illuminate a photosensitive metallic surface of work function \(0.5\) eV. The ratio of the maximum speeds of the emitted electrons is:
1. \(1:2\)
2. \(1:1\)
3. \(1:5\) 
4. \(1:4\)

When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively:

1. 2N and T

2. 2N and 2T

3. N and T

4. N and 2T

A \(5~\text W\) emits monochromatic light of wavelength \(5000~\mathring{A}.\) When placed \(0.5~\text m\) away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved \(1.0~\text m\) away, the number of photoelectrons liberated is reduced by a factor of:
1. \(4\)
2. \(8\)
3. \(16\)
4. \(2\)