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

Plz me asap select the correct text in the passage. which two sentences in the passage introduce counterarguments to the speaker’s position in favor of recycling? we only have a limited number of resources to serve humans around the globe. by recycling and reusing the resources we have, we can preserve what untouched natural resources we have while extending the life of the resources we’re currently using. admittedly, we cannot reuse or recycle all of the materials we use in our daily lives.some materials are not recyclable, such as certain food containers.others items are not biodegradable regardless of what we reuse them for, and that can create problems in the long run. my opponent would use these limitations of our ability to recycle to counter my points about the materials we can recycle.however, this is not an “all or nothing” scenario.we should reuse and recycle the materials that we can and try our best not to buy materials and products that can’t be reused or recycled.by doing our part and encouraging others to do their part, we can increase our chances of conserving our remaining natural and manmade resources over time.

Which work would represent a change to the artistic medium of this original work?

What is the best definition of the underlined word as it is used in the sentence? a statement of wit or amusement an expression of disapproval or condemnation a sentiment of indifference or apathy an exclamation of profound admiration or esteem