Copper is made of two isotopes. copper-63 is 69.17% abundant and it has a mass of 62.9296 amu. copper-65 is 30.83% abundant and it has a mass of 64.9278 amu. what is the weighted average of these two isotopes?

24. a sports ball is inflated to an internal pressure of 1.85 atm at room temperature (25 °c). if the ball is then played with outside where the temperature is 7.5 °c, what will be the new pressure of the ball? assume the ball does not change in volume nor does any air leak from the ball a) 0.555 atm b) 1.74 atm c) 1.85 atm d) 1.97 atm