Which radioisotopes have the same decay mode and have half-lives greater than
hour?
(1) au-198 and n-16 (3) 1-131 and p-32
(2) ca-37 and fe-53 (4) tc-99 and u-233

- lead + phosphoric acid = hydrogen + lead(ii) phosphate

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.