C-14 has a half-life of 5730 years. Suppose you start with 80 grams of C-14. How long will it take until you are left with 40 grams of C-14? 5730 years

11,460 years

2865 years

17190 years

Brainliesttt me asap! the below reaction can be categorized as more than one type of reaction. which reactions are these, and what are the types of reactions?

What must occur for air masses to form fronts

The last few miles of the marathon are the most difficult for heather, her hair plastered to her head, sweat clinging to her arms, and her legs already feeling as if they had nothing left, just dead weight. after grabbing a cup of ice water, she feels the ice cubes smash against her nose as she gulps some cool refreshment and keeps on running. in these last few miles, the breeze kicks up and she finally feels some coolness against her skin. drips of sweat, once clinging to her forehead, now spill down, and heather feels more pain as the sweat flows into her eyes.which of the following is the most likely reason why the ice struck heather’s nose when she took a drink? a) water can function as a solvent. b) water can store large amounts of heat. c) water can moderate temperatures through evaporative cooling. d) the density of water decreases when it freezes. e) water has a cohesive nature.sweat remained on heather’s forehead and arms because of the a) high salt content of sweat b) cohesive nature of water c) ability of water to moderate heat d) high evaporative cooling effect of water e) ability of water to act as a solvent