Answer: Bromine has the highest electronegativity in period 4 of the periodic table.
Explanation:
Electronegativity is defined as the tendency of an atom to attract the shared pair of electrons towards itself whenever a bond is formed.
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:
Potassium is present in Group 1, Period 4 of the periodic table.
Calcium is present in Group 2, Period 4 of the periodic table.
Copper is present in Group 11, Period 4 of the periodic table.
Bromine is present in Group 17, Period 4 of the periodic table.
Hence, bromine will have the highest electronegativity in Period 4.
