Can someone help me to answer this correctly, please, and explain it. Please answer these 3 short questions, I don't have more money to buy more questions. These 3 questions are different.

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An iron nail rusts when exposed to oxygen. According to the following reaction, how many grams of oxygen gas are necessary to form 0.200 moles iron(III) oxide? iron (s)+ oxygen (g) iron(III) oxide (s) grams oxygen gas According to the following reaction, how many grams of mercury(II) oxide are necessary to form 0.426 moles oxygen gas? mercury(II)oxide(s)mercury(I)+oxygen(g) grams mercury(II) oxide An iron nail rusts when exposed to oxygen. According to the following reaction, how many moles of iron(III) oxide will be formed upon the complete reaction of 21.7 grams of iron with excess oxygen gas ? iron(s)+oxygen(g)iron(III)oxide(s) moles iron(III) oxide