The rate of a reaction is essentially the speed at which the reaction proceeds. It is expressed in terms of the amount of reactants consumed or the amount of product formed.
Mathematically, it is the ratio of the change in concentration over a certain time period.
For the given reaction the initial concentration of carbon-dioxide = 0
Final concentration = 24 cm³
Change in concentration = Final - initial = 24 cm³
Titration is a common process used to determine the concentration of acids. It does this by adding a solution of base with a known concentration to the acid until it reaches neutralization.
Acceleration is when something is being moved forward or back, motion is just movement, friction is two or more things rubbing together, so the answer should be B. gravity