If a solution has a perfect neutral ph, what is the concentration of hydrionium ions in the solution

Neutral pH means a pH of 7, yes? Recall that 'pH' means the POWER of Hydrogen. You should be familiar with the equation : pH = -log[H+].

In this case, 7 = log[H+].

Mathematically rearranged, this means that to find H+ concentration,

[H+] = 10 ^-pH.

In this case, [H+] = 10 ^-7.

I am assuming this is conducted at a standard 25 degrees. The auto-dissociation formula of water is this: Kw = [H3O+] x [OH-] at 25 degrees.

The concentration of Hydronium is the same as the concentration of hydrogen, 10 ^-7.  mol/L.

There's your answer!

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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