This question concerns compounds A, B, C and D and processes I, II and III. Compound A is an alcohol, B is an alkene, C is a carboxylic acid, and D is an ester. Determine their structures.

Here's a step-by-step solution to question 5:

5. This question concerns compounds A, B, C and D and processes I, II and III

Based on the given information:

• Compound A is an alcohol (C$_x$H$_y$OH).
• Compound B is an alkene (C$_x$H$_{16}$).
• Compound C is a carboxylic acid (C$_x$H$_y$COOH).
• Compound D is an ester (C$_x$H$_y$COOCH$_3$).

From B (C$_x$H$_{16}$), since it's an alkene, its general formula is C$_n$H$_{2n}$.
So,