The half-life of cesium-137 is 30 years. Suppose we have a 180 mg sample. Find the mass that remains after t years. Let y(t) be the mass (in mg) remaining after t years. Then we know the following. y ( t ) = y ( 0 ) e k t = ⋅ e k t Since the half-life is 30 years, then y ( 30 ) = mg. Thus, e 30 k = . Therefore, k = . Now, remembering that ln x n = n ln x and that e ln z = z , we have y ( t ) = 180 e ( t / 30 ) ( − ln 2 ) = mg. How much of the sample remains after 70 years? After 70 years we have the following. y ( 70 ) = 180 ⋅ 2 = mg (Round your answer to two decimal places.) After how long will only 1 mg remain? To find the time at which only 1 mg remains, we must solve 1 = y ( t ) = 180 ( 2 − t / 30 ) , and so we get the following. t = − 30 log 2 ( ) Hence, we conclude the following. t = yr (Round your final answer to one decimal place.)

In pqr m< p=60 m< q= 30 and m

These questions are based on the attached photo. the experiment is about burning magnesium metal with oxygen. 1. write the balanced chemical equation for the reaction you are performing. 2. calculate the mass of magnesium metal used in each trial. o trial 1: o trial 2: 3. calculate the actual yield of magnesium oxide for each trial. o trial 1: o trial 2: 4. magnesium is the limiting reactant in this experiment. calculate the theoretical yield of mgo for each trial. o trial 1: o trial 2: 5. determine the percent yield of mgo for your experiment for each trial. o trial 1: o trial 2: 6. determine the average percent yield of mgo for the two trials. your company currently uses a process with a similar cost of materials that has an average percent yield of 91 percent. if the average percent yield of this process is higher than that, this could save the company money. what is your recommendation to the company? support your recommendation using your data, calculations, and understanding of stoichiometry gathered from this lab.

The gulf stream is a warm water current that flows away from the equator to northern europe. witch of these does it cause. a. crashes of warm and cool water in the ocean b. colder climates near the equator c. large waves on the cost of europe d. warm climates in northern europe