Cobalt-60 can be used by scientists for the purpose of radioactive dating. cobalt-60 has a half-life of 5,272 years. a fossilized rock originally contained 25 grams of co-60. when tested, the rock only contains 6.25 grams of co-60. approximately how old is the item?

a) 2,600 years

b) 5,200 years

c) 10,500 years

d) 15,600 years
the correct answer is c

Which compound contain an iron with a 3+ charge

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added