If three half lives have passed since a scientist collected 100 grams of sodium 24 , how much Na-24 is left now? 0 grams
24 grams
50 grams
12.5 grams
100 grams

Which of the following is most important in making the typical seed more resistant to adverse conditions than the typical spore? a) a different type of sporopollenin b) an internal reservoir of liquid water c) integument(s) d) ability to be dispersed e) waxy cuticle

Some tools have graduations to show multiple measurements. for example, a ruler may have graduations for both millimeters and centimeters. when measuring the length of an earthworm, which graduations would allow for the most accurate measurement? millimeters centimeters decimeters meters

Explain the process that creates the heat of the sun?