Hi Ranjeet
I completely agree with both Fayiqa Naqshbandi and Gokul Boro.The frequency spacing between two consecutive subcarriers is 1.25 GHz and the subcarriers are numbered like 1,2..so on . By multiplying each of them by frequency gap, we get 1.25 GHZ 2.50 GHz respectively. Hope this helps.
Thanks and regards
Sahil Singh