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					 When ultraviolet radiation is incident on a surface, no photo electrons are emitted. If a second beam causes photo electrons to be ejected, it may consists of
 
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- infra-red waves
 - X-rays
 - visible light rays
 - radio waves
 
 
Correct Option: B
Energy of photon of X-rays is more than energy of photon of ultraviolet rays. Because frequency of X rays is more than ultraviolet ultraviolet rays.