Question

You are given the following molecular formulae of some hydrocarbons:
C₅H₈; C₇H₁₄; C₆H₆; C₅H₁₀; C₇H₁₂; C₆H₁₂

Which three formulae can represent cyclic hydrocarbons?

 

Answer 1

C₇H₁₄, C₅H_10, C₆H₁₂ are the three molecular formulae which represent cyclic hydrocarbons, as they correspond to the general formula C_nH_2n, where n is the number of carbon atoms in its one molecule. The closed chains of cyclic hydrocarbons contain as many carbon atoms as denoted by their molecular formulae. Therefore, a cyclic hydrocarbon containing 7 carbon atoms will be a closed cycloheptane, a cyclic hydrocarbon with 5 carbon atoms will form a pentagonal ring called cyclopentane and a cyclic hydrocarbon with 6 carbon atoms will form a cyclohexane.