1) Californium-253 has a half-life of 18 days. Calculate how long it would take for the radioactive count in a sample to decrease from 4Bq to 0.25Bq (2 marks) 2) Carbon – 14 has a half-life of 5700 years. A count begins at 200 and many years later the count is done again and it is now 150. How many years later was that second count done? (2 marks)

3) The radioactive count of Rn-222 takes a 30.4 days to fall from 80000Bq to 312.5Bq. What is the half-life of Rn-222? (2 marks)

4) A man has just found what he believes to be a really old coin with his metal detector. Upon testing in the laboratory, the coin is found to have a C-14 reading of 1.6Bq. If the coin is believed to be 11400 years old and the half-life of C-14 is 5700 years, estimate the reading on the coin when it was new (3 marks)

5) The isotope Pu-238 has a half-life of 87.7 years and can be used to power generators. A generator contains 925g of Pu-238 and 1g of Pu-238 has a powe

Read the excerpt from elie wiesel’s all rivers run to the sea. why were those trains allowed to roll unhindered into poland? why were the tracks leading to birkenau never bombed? i have put these questions to american presidents and generals and to high-ranking soviet officers. since moscow and washington knew what the killers were doing in the death camps, why was nothing done at least to slow down their “production”? that not a single allied military aircraft ever tried to destroy the rail lines converging on auschwitz remains an outrageous enigma to me. birkenau was “processing” ten thousand jews a day. stopping a single convoy for a single night—or even for just a few hours—would have prolonged so many lives. based on the paragraph, the author would most likely agree that it is best to avoid confrontation at all costs. people need to be proactive when they witness an injustice. countries should remain neutral to keep alliances strong. moscow and washington are to be blamed for the holocaust.

The following question asks about one or more selections from your literature textbook. you may use your textbook to answer this question. both “lob’s girl” and “jeremiah’s song” contain flashbacks. in a paragraph, explain what this plot technique adds to the stories. support your answer with one detail from each story.

As you read in this lesson, satire depends on the audience recognizing and agreeing with the satirist’s implicit criticism of his or her target. how effective can satire be in shaping behavior or opinions if the audience is always in on the joke and thus never the target? your answer should be at least 250 words.