Heeep it's just earth-space science Diagram and graph the first, second, and third half-life of a rock sample that has 16 grams of a radioactive element.

Ineed with these last two questions: 1) what are two types of cold air masses that influence the weather in north america? name them and describe their humidity. 2) describe the motion of a cold air mass and a warm air mass and the weather you would expect at a warm front and an occluded front.

Need in all of themmm only answer if you know plsssss

Who was the first scientist to measure speed as distance over time?