<prompt> Alpha paicle has: September 20111 proton, 2 neutrons1 proton, 1 neutron2 protons, 1 neutron2 protons, 2 neutrons  <response>: Ans. D: 2 protons, 2 neutrons Alpha paicles are simple helium nuclei i.e. consisting of 2 protons and 2 neutrons Remember: Alpha rays: Most ionizing Gamma rays: Maximum penetration power Cesium-137, cobalt and radium emits predominantly: Gamma rays 