Write Lewis structures that obey the octet rule for each of the following, and assign oxidation number, and formal charges to each atom: (a) OCS, (b) SOCl_2 (S is the central atom), (c) BrO_3^-, (d) HClO_2 (H is bonded to O) What is the oxidation number of Cr_2 O_7^2-? Draw the Lewis structure for each of the following molecules or ions, and predict their electron-domain and molecular geometries: (b) CH_3^+, (c) BrF_3, (d) ClO_3^-, (f) BrO_2^-.