KVPY SX SB Exam 2018 Question Paper

Hint −> See the hydrogen bounded structure of A−T (Adenine - Thymine) and - G-C(Guanine- Cytosine)
Solution :
⇒ No OH bond between A−T=2
Average energy of each H bond in A−T pair =X Kcal mol−1
Total no of A−T pair in structure =5
Hence, total energy =2x×5=10x
→ No of H bond between G−C=3
Average energy of each H-bond in G-C pair = Y Kcal mol−1
Total no of G−C pair in structure =3
Hence total energy =3y×3=9y
-> Now, the total energy required to split all double-stranded DNA into two single strands.
=10x+9y