Anugget of gold with a mass of 521 g is added to 50.0 ml of water. the water level rises to a volume of 77.0 ml. what is the density of the gold?

a). 10.4g/ml
b). 6.77g/ml
c). 1.00g/ml
d). 0.0518g/ml
e). 19.3g/ml

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.