The half-life of cobalt-60 is 5.3 years. if you have a sample that contains 10.0 g of the isotope, how much will be left after 15.9 years? a. 2.5 g b. 5.0 g c. 1.25 g d. 0.625 g

Suppose while hauling rocks, you accidentally drop one. it breaks apart in flat, planar sections. what type of rock did you just drop? 20 points

Polly is pushing a box across the floor with a force of 30 n. the force of gravity is –8 n, and the normal force is 8 n. which value could describe the force of friction if polly could not move the box?

Which best term to describe a chemical reaction that absorbs energy from its surroundings? a.thermal conductor b.thermal insulator c.endothermic d.exothermic