Would someone check my answers? . 1. which of these pairs of elements is most likely to be part of a polyatomic ion? . rb and cl. ba and o < . c and n. 2. which of the following element combinations will likely form polyatomic ions? . oxygen and carbon < . sodium and bromine. xenon and neon. cesium and chlorine. k and br. 4. which of the following ions is not an oxyanion? . co^3^2-. cn-. so^4^2-. no-