Which of the following statements is true about the periodic table? the atomic radius increases moving down a column. the atomic radius decreases moving down a column. the chemical reactivity of metals increases moving from left to right. the chemical reactivity of nonmetals decreases moving from left to right.

option (a) is the correct answer.

Explanation:

In a periodic table, when we move from top to bottom in a periodic table then there will be increase in number of shells because of addition of more number of electrons.

As a result, there will be increase in atomic radius of the atom.

Metals are the elements which have excess of electrons but on moving from left to right in a periodic table reactivity of metals decreases as there valence shells does not contain extra electrons to donate.

On the other hand reactivity of non-metals increases on moving from left to right.

Hence, we can conclude that the statement atomic radius increases moving down a column, is true about the periodic table.

it should be all of them because it asks if you included all of those in your answer

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.