Fill in the missing values in the table.
a =
b =
c =

These are experimentally reported values , The values are

A = Bromine = 1.12 Angstrom

B = Magnesium =  1.6

C = Sodium = 1.9

Order of Atomic radius :

Sodium > Magnesium >Phosphorus > Bromine > Chlorine

Explanation:

In order to explain the answer , look some basic concepts of the periodic table:

The periodic table is the arrangement of element in increasing order of their atomic number.

Modern periodic table is divided into two parts :

1. Periods : The horizontal rows are called the periods. There are seven periods in the periodic table.The period of the element tells about the electron shell.

For example the element of period 2 = contain  2 shell( from Li to Neon)

Along the period the atomic size decreases. This is because the effective nuclear charge increases along the period

2. Groups : The vertical columns are called the groups . The group number of the element tell about the number of electron in outermost shell.

For example the element of group 3 = has 3 electrons in their outermost shell(Boron , Aluminium , Gallium , Indium , Thallium)

Down the group the atomic size increases because each the number of shells increases on going down.

For example example :

Boron = 2 shells

Al = 3 shell , In = 4 shells

The given table is :

Bromine = 1.12

Chlorine = 0.97

Magnesium = 1.6

Sodium = 1.9

Phosphorus = 1.28

Order of size :

Sodium > Magnesium >Phosphorus > Bromine > Chlorine

How to proceed :

1. First , find out their atomic number

Bromine = 35

Chlorine = 17

Magnesium = 12

Sodium = 11

Phosphorus = 15

2.Find the electronic configuration :

Bromine = [Ar] 3d10 4s2 4p5

Chlorine = [Ne] 3s2 3p5

Magnesium = [Ne] 3s2

Sodium = [Ne] 3s1

Phosphorus = [Ne] 3s2 3p3

3. Check the elements which belong to halogen family : They have smallest atomic radii. Here, Bromine and chlorine .

These have smallest size because of more effective nuclear charge.

.(These elements are present on Right  side of the periodic table)

But Bromine = 4 shell and chlorine =3 shell

So Cl = smallest radii

Hence,radii Bromine > Chlorine

4 .Check the elements which belong to "Alkali "family : They have largest atomic radii. Here sodium.(These elements are present on extreme left side of the periodic table)

So Size , of sodium = maximum

Then search the alkaline metal ion : These are large in  size , also present on left side of periodic table

Hence

Magnesium is second large atom

So trend is :

Sodium > Magnesium >Phosphorus > Bromine > Chlorine

it's all four options.