NEET Class neet Answered

Phosphodiester bond is between PO4- group and sugar. 
Since our DNA is 1000bp long, it means it has 1000 bases each strand. And, each base is connected to sugar. 
Each sugar is bonded to other by phosphodiester bond except the first one (5′ end) and last one ( no phosphate justOH 3′). 
So, the number of phosphodiester bond is 999.
We need to double this number because 1000bp DNA means double stranded DNA. So, total Phosphodiester Bond = 999 + 999 = 1998
Each base pair of DNA has two pentose sugars and phosphate molecules and two glycosidic linkages as DNA is double stranded structure.

Therefore, total number of phosphates = 2000.