1. A student uses a mass balance that is precise to the nearest decigram to measure 225.4 grams of fresh soil. The student then uses a digital scale that is precise to the nearest
milligram to measure 1.422 grams of topsoil. What is the total mass of soil, in grams, that the
student has measured? Record your answer to the appropriate number of significant digits.

Only one reactant yields 2 or more products. meaning you will only have 1 product and it will break down into 2 or more products. eg. h2o -> h2 + o2

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.

1. why does the same side of the moon always face earthc.the rotational period of the moon is equal to one revolution around earth2. which is greater the moons period of rotation or its period of revolution  b.the moons revolution period around earth3.what was the major accomplishment of the apollo missions  d.landing on and exploring the moon4. which of these space missions involved the deployment of lunar rovers d.apollo5. which scientists are going to explore next on kepler-186fd. evidence of existence of life6.which mission is not going to explore the outside of the solar systemb.safir7.which technology limit the future of space exploration b. scientist must first develop certain technologies before missions can be completed.