a) $\text{HCl}$ pH Hesabı:
$[\text{H}^+] = [\text{HCl}] = 5 \times 10^{-3}\text{ M}$
$\text{pH} = -\log[\text{H}^+] = -\log(5 \times 10^{-3}) = 3 - \log(5) \approx 3 - 0.70 = \mathbf{2.30}$

b) $\text{NaOH}$ pH Hesabı:
$[\text{OH}^-] = [\text{NaOH}] = 5 \times 10^{-3}\text{ M}$
$\text{pOH} = -\log(5 \times 10^{-3}) = 2.30$
$\text{pH} = 14 - \text{pOH} = 14 - 2.30 = \mathbf{11.70}$