If 4 moles of P is used by 5 mole of O2
then....0.489 moles will be used by 5/4 × .489 = .611 moles of O2
so .611 moles
so if 4 moles of P is burnt , 1 mole of P4O10 is produced ....so for .489 moles...... .489/4=.122 moles !
so mass will be .122× 283.89 = 34.7 grams
so first ans is .611 moles and second is 34.7 grams !
if you have any problem regarding this , just comment !!!
Answer:
because the number of electrons and protons differs
6-(2+4)
6-6
=0 Formal charge of O atoms a and b is 0
6-(1+6)
6-7
= -1 Formal charge for O atoms c is -1
Answer 0,0,-1