If you look at the periodic table today which elements would best represent a triad as predicted by Dobereiner? A. Hydrogen Oxygen Nitrogen
B. Nickel Copper Zinc
C. Aluminum Gallium Indium
D. Neptunium Plutonium Americium
E. All of them are triads
HELP ME PLEASE

 B. Nickel Copper Zinc

Explanation:

Dobereiner's triads was a group of three elements. Dobereiner said that the relative atomic mass of the middle element in each triad was average of the relative atomic masses of the other two elements.

Thus if A, B and C forms Dobereiner's triads, the mass of B is average of mass of A and C.

A. Hydrogen Oxygen Nitrogen:

mass of oxygen = 15.999

mass of oxygen according to Dobereiner =

B. Nickel Copper Zinc

mass of copper = 63.5

mass of copper according to Dobereiner =

C. Aluminum Gallium Indium

mass of gallium = 69.72

mass of gallium according to Dobereiner =

D. Neptunium Plutonium Americium

mass of Plutonium = 244

mass of Plutonium according to Dobereiner =

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.