Why is photosynthesis an endothermic reaction?

The chemical bond connecting one nucleotide with the next one along the nucleic acid chain is called a

Butane gas reacts with oxygen gas to give carbon dioxide gas and water vapor (gas). if you mix butane and oxygen in the correct stoichiometric ratio, and if the total pressure of the mixture is 390 mmhg, what is the pressure (in mmhg) of water vapor after the reaction is completed (temperature and volume do not change).

An engineer wishes to design a container that will hold 12.0 mol of ethane at a pressure no greater than 5.00x10*2 kpa and a temperature of 52.0 degrees celsius. what is the minimum volume the container can have?