Chemistry - Concentration Terms Question with Solution | TestHub

Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations
$1.$$60$$\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{10 }}\mathrm{H}\mathrm{C}\mathrm{l}+40$$\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{10 }}\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$
$2.$$55$$\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{10 }}\mathrm{H}\mathrm{C}\mathrm{l}+45$$\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{10 }}\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$
$3.$$\mathrm{75 }\mathrm{}\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{5 }}\mathrm{H}\mathrm{C}\mathrm{l}+25$$\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{5 }}\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$
$4.$$100$$\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{10 }}\mathrm{H}\mathrm{C}\mathrm{l}+\mathrm{100 }\mathrm{}\mathrm{m}\mathrm{L of }\frac{\mathrm{M}}{\mathrm{10 }}\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$
pH of which one of them will be equal to 1?