At 25 °C, how many dissociated H+ ions are there in 345 mL of an aqueous solution whose pH is 11.87?

Ithink it’s one of those things that you put the object on

  balanced chemical equations follow the law of conservation of mass and charges. the masses and charges on either sides of the equation should be balanced.in conservation of mass, the number of atoms of each element on left side should be equal to the number of atoms of each element on the right side of the equation.1)k₂so₄ + 2ca(no₃)₂ --> 2kno₃ + 2caso₄number of ions        left side             right side  k⁺         2                         2so₄²⁻   1                         2ca²⁺     2                         2no₃⁻     4                         2in this equation the masses of so₄²⁻ and no₃ are not balanced. therefore this equation violates the law of conservation of mass2)ti + 2 cl₂ > ticl₄        left side       right side  ti           1               1cl           4               4this equation follows the law of conservation of mass3)2c₂h₂ + 5o₂ > 4co₂   + 2h₂o              left side     right side  c               4               4h               4               4o             10             10this equation follows the law of conservation of mass4)baso₄ + 2naoh --> ba(oh)₂   + na₂so₄          left side       right side  ba       1                   1so₄²⁻     1                   1na         2                   2  oh⁻       2                   2this equation follows the law of conservation of massanswer is 1st equation