Finding number of moles

Calculate how many moles of hydronium ion are in $1.50*10^2$ milliliters of solution, and report your answer using correct rules for significant figures.

solution $4.10*10^{-6}$ M


By DEFINITION a solution which is 1M has 1mol/liter dissolved substance.

Therefore the number of moles of hydronium in a $4.1*10^-6 M, 1.5*10^2$ ml solution is:

$N = 4.1*10^(-6)*1.5*10^2*10^(-3) = 6.15*10^(-7)$ moles