Write the equation for the acid dissociation, write the Ka expression, solve for Ht concentration, then do an ICE chart. Put the values into the Ka expression (the one you solved for Ht and find Ht, convert to pH and input that to 2 decimal place. Or use the Henderson-Hasselbalch equation: pH = pka, + log ( Base/Acid)
Calculate the pH of a buffer solution consisting of 0.39 M HA (Ka = 8.8 x 10^-6) and 0.2 M NaA.

The pH of the buffer is 4.77

Explanation:

Using Henderson-Hasselbalch equation we can solve the pH of the buffer:

pH = pKa + log [A⁻] / [HA]

Where pH is the pH of the buffer

pKa is -log Ka = 5.056

[A⁻] = [NaA] = 0.2M

[HA] = 0.39M

Replacing:

pH = 5.056+ log [0.2] / [0.39]

pH = 4.77

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6