A student in science class is asked to sketch a basic model of an animal cell using only three essential features. The student must select the most crucial organelles to draw for a new student to understand the basic structure of an animal cell. Which of the following structures would be best to include in this basic model? (DOK 2)

To calculate the concentration of the base based on the titration, the concept used is the equal of number of equivalence of the acid used to that of the base. From this,
                                 Na x Va = Nb x Vb
For HBr and KOH, molarity is equal to normality. Substituting the known values,
          (0.75 M) x (22.6 mL - 0 mL) = Nb x (37.5 mL - 0.5 mL) 
                                         Nb = 0.46 N
                                          Mb = 0.46 M
Thus, the concentration of the base is approximately 0.46 M.