In this experiment, direct titration of a base with acid is not used. instead, a back titration of a base with excess acid will be employed. why?

a. the co2 gas is released during the chemical reaction and is a slow step
b. there is a time delay between the addition of the acid and the completion of the reaction
c. the endpoint of the titration would be unclear because straight titration does not allow enough reaction timed
d. none of the above
e. all of the above

None of the options are not used in this experiment, hence "all of the above" is the correct answer.

Option: E

Explanation:

In the above experiment "back titration" is opted because of the need to determine "strength of an analyte" as "molar concentration" of an excess reactant is known. It is done when acid or mostly base is an insoluble salt, when reaction take palce very slowly and definitely when endpoint would be hard to discern for example titration of weak acid and weak base. The procedure to follow back titration is firstly the volatile analyte is reacted with an excess reagent then the titration is done on remaining amount of known solution.