The electron configuration for Helium (He) is shown below. 1s2

Which diagram shows the correct distribution of electrons in the electron shells of a helium atom?

A gray circle labeled 1 P 0 N is surrounded by a concentric circle with one gray dot at the north position.

A gray circle is labeled 5 P 6 N. It is surrounded by two concentric circles. The inner circle has gray dots at the north and south positions. The outer circle has three evenly spaced dots; none of these align with the dots in the inner circle.

A gray circle is labeled 2 P 2 N. A concentric circle surrounding it has two gray dots, at the north and

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.