Arrange the halogens F2 , Cl2 , Br2 , I2 , in order of their increasing reactivity with alkanes. (i) I2 < Br2 < Cl2 < F2 (ii) Br2 < Cl2 < F2 < I2 (iii) F2 < Cl2 < Br2 < I2 (iv) Br2 < I2< Cl2 < F2