The number of molecules that are in balloon are = 2.227 x10^23 molecules
calculation
calculate the number of moles of NO
moles = mass/molar mass
molar mass of NO = 14+ 16 = 30 g/mol
moles is therefore= 11.1 g/30g/mol= 0.37 moles
by use of Avogadro's constant that is
1 mole= 6.02 x10^23 molecules
0.37 =? molecules
=(6.02 x10^23 x 0.37 moles)/ 1mole=2.227 x10^23 molecules