Correct Answer: 3.25x10^-3M

The above reaction is categorized as acid base reactions. This type of reaction is usually the result of an acid (H⁺ proton donor) reacting with a base (OH^- proton acceptor) to form products and water according to the equation;

Using the mole theory we know that 1 mole of H⁺ will react completely with 1 mole of OH^-. Based on this and the information in the question above, it is then possible to calculate the concentration of H+ ion in the acid rain.

Answering the question:

The molarity of the H+ in the acid rain can be determined by calculating the number of moles of NaOH used to neutralize it.

0.010M of NaOH contains 0.010 moles of NaOH in 1000ml

Therefore 1ml of solution would contain 0.010/1000 moles or 0.00001moles

This means 6.5ml would contain 6.5 x 0.00001 or 0.000065 moles or 6.5x10^-5 moles

Now based on the fact that 20ml of acid rain was neutralized by 6.5ml of NaOH, and the relationship of H+ and NaOH follows the ratio;

Thus 1 mole of H⁺ requires 1 mole of NaOH to completely react.

Therefore 20.0-milliliters of acid rain contains 6.5x10^-5 moles of H⁺ ions. The molarity of H+ is the number of moles in 1000ml is 1000/20 x 6.5x10^-5 moles which is equal to 0.00325M or 3.25x10^-3M

Giving an answer of 3.25x10^-3M