To find the molecular formula, first determine the empirical formula from percentage composition, then scale it using the molar mass. Carbon is 92.3%, so hydrogen is (100 - 92.3 = 7.7%). Moles ratio: C (= 92.3/12 = 7.69), H (= 7.7/1 = 7.7). Dividing by the smaller value: C (\approx 1), H (\approx 1). Empirical formula is (\text{CH}) with empirical mass (= 13) g/mol. Multiplying factor (n = 78/13 = 6). Therefore molecular formula is (\text{C}_6\text{H}_6) (benzene). Option (\text{CH}) is the empirical formula only, not the molecular formula with molar mass 78. Option (\text{C}_2\text{H}_2) has molar mass 26, inconsistent with 78 g/mol ((n) would be 3, giving (\text{C}_6\text{H}_6), but (\text{C}_2\text{H}_2) itself is wrong). Option (\text{C}_3\text{H}_4) has molar mass 40, which does not divide 78 to give an integer. This is a classic NCERT empirical-to-molecular formula problem. Plausibility check: (\text{C}_6\text{H}_6) has molar mass (6(12)+6(1)=78) g/mol, confirming the answer.