How would you identify substances in a question

How much energy moves onto the next level, in an energy pyramid

Calculate - analysis of compound composed of iron and oxygen yields 174.86 of fe and 75.14g of o. what is the empirical formula for this compound?

22. a flask containing 450 ml of 0.50 m h2so4 was accidentally knocked to the floor. how many grams of nahco, do you need to put on the spill to neutralize the acid according to the following equation: h2so4(aq)+2 nahcos(aq) na,so(aq) +2 h20()+2 co2(g) d) 38 g a) 2.3 g b) 9.5 g c) 19 g