For a double strand DNA, one strand is given below:

The correct answer is 41.

1. Understanding DNA Base Pairing and Hydrogen Bonds:
In a double-stranded DNA molecule:
• Adenine (A) pairs with Thymine (T) via 2 hydrogen bonds (A = T).
• Guanine (G) pairs with Cytosine (C) via 3 hydrogen bonds (G ≡ C).

2. Analyzing the Given DNA Strand from the Image:
The given sequence from 5' to 3' is:

Sequence: 5' - A - G - T - C - A - C - G - T - A - A - G - T - C - 3'

Let's count the total number of nitrogenous bases present in the single strand:
• Number of Adenine (A) bases = 4 (at positions 1, 5, 9, 10)
• Number of Thymine (T) bases = 3 (at positions 3, 8, 12)
• Number of Guanine (G) bases = 3 (at positions 2, 7, 11)
• Number of Cytosine (C) bases = 3 (at positions 4, 6, 13)
Total bases = 4 + 3 + 3 + 3 = 13 bases.

3. Determining Base Pairs in the Double Strand:
• Number of A-T base pairs = (Number of A) + (Number of T) = 4 + 3 = 7 base pairs.
• Number of G-C base pairs = (Number of G) + (Number of C) = 3 + 3 = 6 base pairs.

4. Calculating the Total Number of Hydrogen Bonds:
• Hydrogen bonds from A-T base pairs = 7 × 2 = 14 H-bonds.
• Hydrogen bonds from G-C base pairs = 6 × 3 = 18 H-bonds.
• Total number of H-bonds = 14 + 18 = 32 H-bonds.

5. Energy Calculation:
From the given data in the image:
• Average energy per H-bond for A-T base pair = 1.0 kcal mol^-1
• Average energy per H-bond for G-C base pair = 1.5 kcal mol^-1

Now, calculate the total energy required to split the double-stranded DNA into two single strands by breaking all hydrogen bonds:

$\text{Energy for A-T pairs}=14\times 1.0\text{kcal mol}{-1}^{}=14\text{kcal mol}{-1}^{}$

$\text{Energy for G-C pairs}=18\times 1.5\text{kcal mol}{-1}^{}=27\text{kcal mol}{-1}^{}$

$\text{Total Energy}=14+27=41\text{kcal mol}{-1}^{}$

Therefore, the total amount of energy required to split the double-stranded DNA into two single strands is 41 kcal mol^-1.