Explain why a dead tree would still be a biotic factor, even though it is no longer alive?

Plz me get these answer dubble cheak ur answer plz ppl i need it right

Draw the structure for 5-isopropyl-2-methyl-3-nonene

For the reaction shown, calculate how many moles of no2 form when each of the following completely reacts. 2n2o5(g)→4no2(g)+o2(g) part a 1.0 mol n2o5 express your answer using two significant figures. nothing mol m o l request answer part b 5.4 mol n2o5 express your answer using two significant figures.