On a hot summer day the temperature is 35°c, barometric pressure is 103 kpa, and the relative humidity is 90%. an air conditioner draws in outside air, cools it to 20°c, and delivers it at a rate of 12,500 l/h. calculate the rate of moisture condensation (kg/h) and the volumetric flow rate of the air drawn from the outside.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

they are made of gases.

they have a spherical shape.

they make energy through fusion.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.