Test Yourself 1- Which is larger:
a) Million or billion?
b) A part of million or a part of billion?
2- Which is more harmful: concentration of a poisonous substance (lead) in
drinking water to be a part of a billion or a part of a million?

Answer is (d)a brainliest would be appreciated

Ibelieve the answer is d. bleachhope my answer has you : )

Answer:             1.0  × 10⁻⁵ msolution:                     as we know ph is given as,                                    ph  = -log [h⁺]and,                                    [h⁺]  =  10^-ph    (1)putting value of ph in eq. 1,                                    [h⁺]  =  10⁻⁵                                    [h⁺]  =  1.0  × 10⁻⁵ m