21. A block of gold has a mass of 5.3 Kg. How many troy ounces of gold have? a. 170 oz c. 1.7 oz
b. 340 oz d. 1700 oz
22. You drive to Roswell, 73 miles, in 65 minutes. How fast did you drive in Km/hr?
a. 54 Km/hr c. 108.5 Km/hr
b. 41.8 Km/hr d. faster than the speed limit

Answer asap need to be answered 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.