Calculate the mass in grams of each sample. Express your answer using two significant figures.
A.4.88x10^20 H2O2 molecules
B. 2.1x10^22 SO2 molecules
C. 5.3x10^25 O3 molecules
D. 9.12x10^19 CH4 molecules

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.

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

Ab c or d ? i’m not sure what the answer is