The formula for pH calculation is -log10[H+].

Explanation:
pH is a measure of the acidity or alkalinity of a solution and is defined as the negative logarithm (base 10) of the concentration of hydrogen ions, [H+], in a solution. The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral, pH less than 7 indicates acidity, and pH greater than 7 indicates alkalinity.

Let's break down the formula for pH calculation:

- The negative sign (-) indicates that we are taking the negative logarithm of [H+].
- The logarithm function is denoted as log10, which means we are taking the logarithm to the base 10.
- [H+] represents the concentration of hydrogen ions in the solution, usually measured in moles per liter (mol/L) or molar (M).

By taking the negative logarithm of [H+], we can convert the concentration of hydrogen ions into a more manageable range of values. For example, a solution with a hydrogen ion concentration of 0.001 M would have a pH of 3, which indicates acidity.

To calculate the pH using the formula, you would:
1. Determine the concentration of hydrogen ions, [H+], in the solution.
2. Take the negative logarithm (base 10) of [H+] using the formula -log10[H+].
3. The result gives you the pH value of the solution.

Therefore, the correct formula for pH calculation is -log10[H+], as given in option 'B' of the given choices.