I am not understanding how to solve these problems and get to the correct answers. I need help understanding both why and how things are done. Thank you for your help!

Iron(III) oxide( Fe2O3) reacts with carbon monoxide to form metallic iron and carbon dioxide. When the chemical equation corresponding to this reaction is balanced to lowest possible whole number ratio of the balancing coefficients, the coefficient of iron is: 1 2 4 3 The reaction of sodium phosphate with barium chloride produces sodium nitrate and barium phosphate according to the balanced chemical equation shown. 2Na3PO4(aq)+3BaCl2(aq)6NaNO3(aq)+Ba3(PO4)2(s) How many moles of barium phosphate will form when 35.0mL of 0.300MNa 3PO4(aq) is added to 25.0mL of 0.450MBaCl2(aq), assuming 100% yield? 0.00751mol 0.00375mol 1.13mol 2.26mol Hydrogen has a molar mass many times smaller than that of carbon. If samples of each element have equal masses, which sample has a greater number of moles? the hydrogen sample cannot be determined from given information the carbon sample the number of moles would be equal What is the total ionic equation for the following formula unit equation? HF(aq)+KOH(aq)KF(aq)+H2O(I) HF(aq)+OH(aq)F(aq)+H2O(l) [H+(aq)+F(aq)]+[K+(aq)+OH(aq)][K+(aq)+F(aq)]+[2H+(l)+O2(l)] [H+(aq)+F(aq)]+[K+(aq)+OH(aq)][K+(aq)+F(aq)]+H2O(aq) HF(aq)+[K+(aq)+OH(aq)][K+(aq)+F(aq)]+H2O(l)