Which hypothesis led to discovery of the proton?

When a neutral hydrogen atom loses an electron, and positively-charged particles should remain. A proton should be 1840 times heavier than an electrons. Cathode rays should be attracted to a positively- charged plate.  

There is a positive charge in the nucleus

Explanation:

The concept was envisaged by Ernest Rutherford. He was a renowned scientist and chemist. In the hypothesis, he proposed that an atom must have a concentrated positive charge around the nucleus or in the nucleus that contains the atom's mass. He also suggested that the nucleus contains a particle with a positive charge that was called a proton.

Answer : The amount of gas added, 0.08 mole

Solution :

According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at constant temperature and pressure of gas.

or,

where,

= initial volume of balloon = 500 ml = 0.5 L

= final volume of balloon = 1 L

= initial moles of gas = 0.0400 mole

= final moles of gas = ?

Now put all the given values in the above formula, we get the amount of gas added.

Therefore, the amount of gas added, 0.08 mole