What composition of lead-tin solder is the best choice for joining electronic components. why is this composition chosen?

Air undergoes a constant pressure cooling process with no moisture added or removed. the air originally exists at 45 °c, 150 kpa and 35 % relative humidity. it is cooled until the temperature reaches 29 oc. determine (a) the relative humidity of the cooled air. (b) the dew point temperature of the cooled air in °c. (c) the heat removed during the cooling process in kj/kg. use the psychrometric chart to check your answers (this part will not be graded; however, it will you get comfortable using the psychrometric chart)