1-pentyne consists of a carbon chain of 5 carbons one with a triple bond. 1-octyne is a carbon chain of 8 carbons with a triple bond at some point. It is known that the longer the carbon chain the higher the boiling point since more energy will be required to break the bonds between carbons. Based on this it is predicted that 1-octyne will have a higher boiling point than 1-pentyne.
They both perform photosynthesis and also cell respiration
In a perfect world without air resistance, the top of the swing would have the most potential energy, but the least amount of kinetic energy. As the pendulum falls down, it gains more kinetic energy as it travels faster due to gravitational acceleration but loses more potential energy as it loses height. The total amount of energy in the system (the sum of kinetic and potential energy) stays the same.