The balanced equation is :
. . . . . . .2 NO . . . + . . . O2 . . . ---> . . . 2 NO2
. . . . . 2 moles . . . . . . . . . . . . . . . . . . 2 moles
NO : k1 = n(NO) / 2 = 2,9
O2 : k2 = n(O2) / 2 = 5
k1 < k2 . . . then NO is the reagent limiting
According the equation :
. . . . . . 2 mole of NO gives 2 moles of NO2
. .then 5,8 moles of NO gives 5,8 moles of NO2
According the equation :
. . . . . . 2 mole of NO requires 1 mole of O2
. .then 5,8 moles of NO requires 5,8 / 2 = 2,9 moles of O2
There is 10 - 2,9 = 7,1 moles of O2