What is the electron configuration of an element with atomic number 20? a. 1s2 2s2 2p6 3s2 3p5 b. 1s2 2s2 2p6 3s2 3p6 c. 1s2 2s2 2p6 3s2 d. 1s2 2s2 2p6 3s2 3p6 4s2 e. 1s2 2s2 2p6

Electric charge is what ? a. kinetic energy b. radiation c. discovery d. electricity

Aconcentrated solution of ammonia is 14.8m and has a density of 0.899g/l. what is the concentration of ammonia in this solution in weight percent (%w/w)?

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.