What would you have to do to develop a theory of atoms?

Avolleyball player hit a ball with a mass of 0.25 kg. the average acceleration of the ball is 15.5 m/s². how much force did the volleyball player apply to the ball? 62.0 n 3.87 n 62.0 m/s² 3.87 m/s²

Boron has an average atomic mass of 10.81. one isotope of boron has a mass of 10.012938 and a relative abundance of 19.80 percent . the other isotope has a relative abundance of 80.20 percent what is the mass of that isotope? report two decimal places

How much heat (in kj) is evolved in converting 1.00 mol of steam at 130.0 ∘c to ice at -55.0 ∘c? the heat capacity of steam is 2.01 j/g⋅∘c and of ice is 2.09 j/g⋅∘c?