Can someone please please help me!!

219 grams of iron (iii) oxide reacts with excess carbon according to the reaction equation shown below. fe2o3 + c → fe + co2 after a scientist performs the chemical reaction they find the actual yield of iron to be 57.4 grams. calculate the percent yield of this chemical reaction.

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?

Upon decomposition, one sample of magnesium fluoride produced 1.65 kg of magnesium and 2.56 kg of fluorine. a second sample produced 1.32 kg of magnesium. part a how much fluorine (in grams) did the second sample produce?