A substance has a half-life of 100,000 years and an initial mass of 1,000 grams. How many years will pass before only 250 grams of the substance's parent material is left?

Which statements best describe monsoons? check all that apply. they force cool, moist air from oceans to rise. they are winds that blow in the opposite direction of a normal wind. they bring rain in the summer and drought in the winter they increase rainfall in south asia, africa, and australia. they influence precipitation as wind moves near a mountain.