What must astronauts use microphones and headphones in outer space

How many liters of oxygen gas, at standard temperature and pressure, will react with 35.8 grams of iron metal? 4 fe (s) + 3 o₂ (g) → 2 fe₂o₃ (s)

Can someone me with 3 and 4 plz. this is for masteries test.

Five different substances are given to you to be dissolved in water. which substances are most likely to undergo dissolution in water? check all that apply. view available hint(s) check all that apply. sodium fluoride, naf octane, c8h18 propanol, ch3ch2ch2oh potassium iodide, ki benzene, c6h6