Which of the following is an example of a chemical change?

a.
ice melting
b.
pounding gold into a coin
c.
milk souring
d.
a puddle of water evaporating

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.