
Answer;
C7H14O2
Solution;
Isobutyl contains , oxygen, carbon and hydrogen (total mass is 1.152 g)
Mass of carbon = 12/44 × 2.726 g
              = 0.743455 g
Mass of Hydrogen  = 2/18 × 1.116 g
              =  0.124 g
Mass of oxygen = 1.152 - (0.7435 + 0.124)
              =  0.2845 g
Moles of carbon ; Â 0.7435/12 = 0.06196 moles
Moles of hydrogen; 0.124/1 = 0.124 moles
Moles of oxygen; Â 0.2845/16 = 0.01778 moles
Ratios ; 0.06196/0.01778 ; 0.124/0.01778 : 0.01778/0.01778
     =  3.5 :  7.0 : 1
To make them whole numbers ; we multiply the ratios by 2 Â to get;
(3.5 : Â 7.0 : 1 )2 = 7 : 14 : 2
Thus, the empirical formula of Isobutyl propionate  is C7H14O2