Cesium-137 has a half-life of 30 years. If a 40 g sample decays over a period of 90 years, how many grams of cesium-137 would remain?

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Match each object to its description: a. coma of a comet b. comet tail c. oort cloud haze surrounding a nucleus created by solar wind. hypothetical sphere around the solar system

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