Which particle makes the atom an unstable isotope?

Use the table to identify the phase and phase changes of the elements under the given conditions. write the name of the substance, phase, or phase change

Chemistry worksheet - i am not sure what they are asking for exactly?

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