The correct choice is Buffers.
Buffers contains both acids and bases in equilibrium.when base is added to buffers, they adjust the pH value by releasing hydrogen ions.when acid is added to buffers, they adjust the pH value by consuming hydrogen ions. hence these substances resist any change in their pH value by releasing or absorbing hydrogen ions.This process keeps the pH value constant.
Ok so the first thing you need to do is im not gonna help you
Explanation:
Given:
Solving for 
:
where:
Integrating to get 
with initial conditions 
:
Integrating to get x with initial conditions x(0) = 0:
When t=T:
Increased by a factor of 4
