Given:

pH= 3.76

To find out the concentration of hydrogen ion in it, we apply the formula:

pH = -log[H⁺]

where pH is defined as the negative logarithm of the concentration (in mol per litre) of hydrogen ions which it contains.

Using the formula, we write,

log[H⁺] = -pH

By taking antilog of both the sides, we get

[H⁺] = antilog [-pH]

⇒[H⁺] = antilog (-3.76)

⇒[H⁺] = 1.74 × 10^-4

Thus, the concentration of hydrogen ion in the sample of vinegar is 1.74 × 10^-4M