If the distance between two consecutive base pairs is 0 . 34nm and...

Given the distance between two consecutive base pairs is $0 . 34nm = 0 . 34 \times {10}^{- 9}m$.

A total number of bases $= 6 . 6 \times {10}^{9}bp$.

Length of DNA = Total no. of $bp \times$Distance between two consecutive$bp$

$= 6 . 6 \times {10}^{9} \times 0 . 34 \times {10}^{- 9}$

$= 2 . 24m$