Following are the structural formulas and names of four bicycloalkanes. Write the molecular formula of each compound. Which of these compounds are constitutional isomers?

To write the molecular formula of each bicycloalkane, we need to count the number of carbon and hydrogen atoms present in each of the molecules according to the given structural formulas and names.

For each bicycloalkane, we will count the number of carbon atoms (C) and hydrogen atoms (H) to form the molecular formula (CnHm). Compound 1: Bicyclo[2.1.0]pentane In this molecule, there are 5 carbon atoms, and each carbon atom is bonded with two hydrogen atoms, except at the bridgehead carbons, which are only bonded with one hydrogen atom. So we have: Molecular Formula: C5H8 Compound 2: Bicyclo[2.2.0]hexane In this molecule, we have 6 carbon atoms, and each carbon atom is bonded with two hydrogen atoms, except at the bridgehead carbons, where they are bonded with only one hydrogen atom. So we have: Molecular Formula: C6H10 Compound 3: Bicyclo[2.2.0]heptane In this molecule, we have 7 carbon atoms, and each carbon atom is bonded with two hydrogen atoms, except at the bridgehead carbons, where they are bonded with only one hydrogen atom. So we have: Molecular Formula: C7H12 Compound 4: Bicyclo[3.2.0]heptane In this molecule, we have 7 carbon atoms, and each carbon atom is bonded with two hydrogen atoms, except at the bridgehead carbons, where they are bonded with only one hydrogen atom. So we have: Molecular Formula: C7H12

Now that we have the molecular formulas of all four compounds, we can identify the constitutional isomers by looking for compounds that have the same molecular formula but different connectivity of atoms. From the molecular formulas obtained in step 2, we can see that Compound 3 (Bicyclo[2.2.0]heptane) and Compound 4 (Bicyclo[3.2.0]heptane) have the same molecular formula (C7H12) but different connectivity of atoms. Therefore, these two compounds are constitutional isomers.