In a solution labeled "0.10 m hno3," which is correct? [h3o + ]

When 0.1 M HNO₃ is added to water it dissociates as follow,

HNO₃ → H₃O⁺ + NO₃⁻

Let us calculate the pH of this acid in order to know its strength,

As,

pH = - log [H₃O⁺]

Putting H⁺ concentration value,

pH = - log [0.1]

pH = 1

It is highly acidic,

And being strong acid it completely ionizes in water producing only H₃O⁺ and NO₃⁻.

So,

The concentration of H₃O⁺ = 0.1 M

and,

The concentration of NO₃⁻ = 0.1 M