Bodhi

A buffer is created by mixing equal concentrations of NH4+ and NH3. Calculate the volume of both solutions needed to create a buffer of pH=8.75 with a total volume of 100 mL.

A bus service center has 2 feed services that start together at 8 a.m. Bus A leaves at 15 minutes interval, while bus B leaves at 20 minutes interval. On a particular day , how many times do both services leave together from 8 a.m. to 11 a.m.?

I've been able to rule out a few of them, but I'm not sure if it is right, and how to reason one of them. I don't know how to go about reasoning for i). For ii), bond lengths down a group increase, meaning that the compound is more acidic, making this one...

I've gotten so far, but am still unsure of how to proceed. Please correct me if I am wrong: I know that since the concentrations of the base/acid are the same, the log(1) is 0, so the pH = pKa. I determined the Kb by finding the Ka and using the Kw relati...