Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations: a. 60 mL M/10 HCl +40 mL M/10 NaOH b. 55…

Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations : a. $\displaystyle 60 \mathrm{~mL} \frac{\mathrm{M}}{10} \mathrm{HCl}+40 \mathrm{~mL} \frac{\mathrm{M}}{10} \mathrm{NaOH}$ b. $\displaystyle 55 \mathrm{~mL} \frac{\mathrm{M}}{10} \mathrm{HCl}+45 \mathrm{~mL} \frac{\mathrm{M}}{10} \mathrm{NaOH}$ c. $\displaystyle 75$ mL $\displaystyle \frac{\mathrm{M}}{5} \mathrm{HCl}+25 \mathrm{~mL} \frac{\mathrm{M}}{5} \mathrm{NaOH}$ d. $\displaystyle 100 \mathrm{~mL} \frac{\mathrm{M}}{10} \mathrm{HCl}+100 \mathrm{~mL} \frac{\mathrm{M}}{10} \mathrm{NaOH}$ pH of which one of them will be equal to $\displaystyle 1$ ?