11. A fossil is found to contain 20.5g of carbon-14. Using radiocarbon dating methods, you determine the sample originated very close to 17,190 years ago. If the half-life of carbon-14 is 5,730 years, what was the original mass of
the sample?

Abeaker with 2.00×102 ml of an acetic acid buffer with a ph of 5.000 is sitting on a benchtop. the total molarity of acid and conjugate base in this buffer is 0.100 m. a student adds 4.70 ml of a 0.360 m hcl solution to the beaker. how much will the ph change? the pka of acetic acid is 4.740.