Half life of Tc-99 is-

Ans. is 'a' i.e. 6 hours Ionizing radiation emitted by various radioisotopesRays Radioactive elementst 1/2 bP-32Phosphorous14.3 daysSrStrontium28 yearsY-90Yttrium2.54 daysGadolinium does not cross blood brain barrier (BBB) unless the barrier is disrupted b gRa-226Radium1622Au-198Gold2.7 days1-131Iodine (mainly Beta)8 daysgIr-192Iridium74.5 daysCo-60Cobalt5.2 yearsCs-137Cesium30 yearsXe-133Xenon5.2 days1-123Iodine13 hours1-132Iodine2.3 hoursTc-99Technitium6 hoursGa-70Gallium citrate3.2 daysTl-201Thallous chloride3.1 daysRn-222Radon3-6 dayCr-51Chromium K-81Krypton SeSelenium N, gCf-252Californium2.6 yearsTa-182Tantulum4 monthsNote - Radium also emits - a - particles - So, radium emits a, b & g rays. Radium also produces neutrons when mixed with beryllium.