Which statement is true for a solution when its concentration of hydroxide ions becomes equal to the concentration of hydronium ions?

Determine the percent sulfuric acid by mass of a 1.61 m aqueous solution of h2so4. %

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

Kc = 0.040 for the system below at 450oc. if a reaction is initiated with 0.40 mole of cl2 and 0.40 mole of pcl3 in a 2.0 liter container, what is the equilibrium concentration of cl2 in the same system? pcl5(g) ⇄ pcl3(g) + cl2(g)