<u>Answer:</u>
<u>For a:</u> The correct answer is Option (iv)
<u>For b:</u> The correct answer is Option (i)
<u>Explanation:</u>
Atomic radius of an atom is defined as the total distance from the nucleus to the outermost shell of the atom.
On moving from top to bottom, there is an addition of shell around the nucleus and the outermost shell gets far away from the nucleus. So, the distance between the nucleus and outermost shell increases. Thus, increasing the atomic radii of the atom.
On moving from left to right in a period, more and more electrons get add up in the same shell and the attraction between the last electron and nucleus increases, that results in the shrinkage of size of an atom. Thus, decreasing the atomic radii of the atom.
For the given options:
Hydrogen is present in Group 1 and Period 1 of the periodic table.
Helium is present in Group 18 and Period 1 of the periodic table.
Radon is present in Group 18 and Period 6 of the periodic table.
Rhodium is present in Group 9 and Period 5 of the periodic table.
Hence, radon will have the largest atomic radius and the correct answer is Option (iv)
Electronegativity is defined as the the tendency of an element to attract the shared pair of electron towards itself in a compound.
This property of an atom increases as we move from left to right in a period because the number of charge on the nucleus gets increased.
But this property decreases as we move from top to bottom in a group because electrons get add up in the new shells which make them further far away from the nucleus.
For the given options:
Fluorine is present in Group 17 and Period 2 of the periodic table.
Chlorine is present in Group 17 and Period 3 of the periodic table.
Bromine is present in Group 17 and Period 4 of the periodic table.
Hence, fluorine will be the most electronegative atom and the correct answer is Option (i)
