Carbon-14 is a radioactive isotope. The half-life of Carbon-14 is 5,730 years. If 25% of the original Carbon-14 atoms are present in the rock today, how old is the rock?
17,190 years old

11,460 years old

2,865 years old

5,730 years old

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?

What is the magnitude of the gravitational force acting on the earth due to the sun?

How can you improve the percent yield of copper in this lab? check all possible strategies that will you do so. measure reactants precisely. stir to the reaction take place. chill the reactants before combining them. wait patiently until the reaction completes. make sure to recover as much copper as possible.