The pH of a solution is measured to be 5.4. Calculate the following: answers in 2 sig figs. If an exponent is required, then enter the answer in this format: 2.4e-2.

a) [H⁺] = 2.5 × 10⁻⁶ M
b) [H⁺] = 2.5 × 10⁻⁵ M
c) [H⁺] = 2.4 × 10⁻⁶ M
d) [H⁺] = 2.4 × 10⁻⁵ M