True about Cobalt 60 is A/E
High-Yield Explanation
A i.e. Natural radioactive agent Radium has longest half lifeQ (1622 years). It emits a, & YraysQ and it decays to radon. P-32, Sr-90 & Y-90 emits /3 paicles.Q Energy of radiation emitted by Co-60 is 1.173 MevQ; Ra-226 is 0.8 Mev; P-32 is 0.698 Mev; Cs-137 is 0.662 Mev and Ir-192 is 0.47 MevQ Cow is aificially made radeonucliodeQ produced by irradiating ordinary naturally occurring Co-59 with neutrons. Co-60 has atomic number-27, atomic weight 58.93Q, half life 5.3 yearsQ and emits both /3 and y raysQ. It is used in both teletherapy (source of choice) and brachytherapy (but avoided in interstitial implantation)Q. Naturally occurring radioactive nucleide elements belong to one of the 3 series ie 1. Uronium series; 2. Thorium series; 3. Actinum series Cobalt6O and Ir 192 are aificial isotopes