Please help me out with this

Clouds form when water vapor to form small droplets. a. humidifies b. condenses c. evaporates d. precipitates

Which of the following might a chemist choose to study? a. glacier movement in alaska b. better ways to recycle plastics c. the effects of hurricanes on turtle populations d. the vibrations in bridges caused by big trucks

Endeleev saw trends in the physical and chemical properties of elements when he organized them by