Unit of radioactivity is-

Ans is 'a' i.e. Becquerel * Old unit of radioactivity is Curie and new unit (SI) is Becquerel.* Old unit of radiation exposure is Roentegn and new unit (SI) is Columb/cmQuantity measuredOld unitNew (SI)unit RadioactivityCurieBecquerel1 curie = 3.7 x 101 becquerel -2.7 x 10Radiation exposureRoentgenColumb/cm Absorbed doseRadGray100 rad = 1 gray1 rad = 0.01 grayDose equivalentRemSievert (Sv)100 rem = 1 SvIrem = 0.01 Sv