Which pair of formulas correctly represents a molecular formula and its corresponding empirical formula?
(1) c2h2 and ch (3) c4h6 and ch
(2) c3h4 and ch2 (4) c5h8 and c2h2

(1) C2H2 and CH is your answer. An empirical formula only depicts the ratios of how many atoms of each element exist in the compound, and only in this choice is the ratio correct for the molecular formula.

Order of filling levels and sublevels of electrons: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²3f¹⁴5d¹⁰6p⁶for an element with 5 electrons in the 3d energy level: full configuration: 1s²2s²2p⁶3s²3p³.