[02.01]in the 1800s, john dalton's atomic theory proposed that atoms are indivisible. later, subatomic particles such as neutrons, electrons and protons were discovered. what happened to the indivisible part of dalton's atomic theory and why?

There came other atom models: Thompson’s model, Rutherford’s model, Bohr’s model… and finally, Schrödinger’s theory.

Besides, keep in mind that:
-When an atom loses an electron, that electron has to end up in another atom, and then you have cations and anions… and a cation always has to be near an anion… so they are sort of keeping an eye on their missing electrons.
-The only situation where we find isolated neutrons is during nuclear reactions… and remember those are dangerous chain reactions! The atomic bomb is an example of that.
-We can have isolated protons and we call them H+ - so it works as any other cation. You can find H+ in water, where we also have OH-.

Let’s talk about Thompson’s model: They call it the “plum pudding”. It consisted on a large positive charge (the pudding) filled with little negative charges (the plums).

And this is Rutherford’s model: He found out negative charges (electrons) were actually spinning around the positive nucleus. But he didn’t say anything about the shapes or sizes of their orbits.

Then you have the Bohr’s model, also known as the planetary model. Bohr said that there are smaller orbits, closer to the nucleus, and larger orbits, in the outer part of the atom, and did propose a lot of detail about the orbits. But it still wasn’t enough accurate.

Schrödinger’s focused on finding more details about where in the atom you can find each electron, its velocity, its momentum, etc.

Hydrogen is the most abundant element on the periodic table..hope it .

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.