A piece of chalk, has an initial mass of 43. 5 grams. The mass of the chalk decreased to 39. 6 grams after use. Which of these is the closest value to the amount of chalk used?.

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

How many electrons does silver have to give up in order to achieve a sido noble gas electron configuration

Nitrogen (n), phosphorus (p), and potassium (k) are the main nutrients in plant fertilizers. according to an industry convention, the numbers on the label refer to the mass percents of n, p2o5, and k2o, in that order. calculate the n: p: k ratio of a 30: 10: 10 fertilizer in terms of moles of each element, and express it as x: y: 1.0.