The pressure exerted by an individual gas in a gas mixture is defined as the .

partial pressure.

Explanation:

In a mixture of gases each gas exerts the same pressure that it would if it alone occupied the container (Dalton's Law). 2. In a mixture of gases the pressure each gas exerts is called its partial pressure, and the total pressure of the mixture is the sum of the partial pressures of the constituent gases.

Explanation:

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.