HCl is a strong acid and completely dissociates to give out H⁺ ions
Therefore [HCl] = [H⁺]
number of HCl moles - 154 x 10⁻³ g/ 36.5 g/mol = 4.22 mmol
[HCl] = 4.22 x 10⁻³ mol / 0.170 L = 0.025 M
therefore [H⁺] = 0.025 M
by knowing the H⁺ concentration, pH can be calculated
pH = -log[H⁺]
pH = -log (0.025 M)
pH = 1.60