Question

halogens have highest negative gain enthalpies explain​

Answer 1

They have Highest electro negative so they do have...

Answer 2

ʜᴏʟᴀ ᴍᴀᴛᴇ !

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⭐ᴀɴsᴡᴇʀ⭐

The halogen have a strong tendency to accept electrons due to their small size and effective nuclear charge so they have maximum negative electron gain enthalpy in their respective periods of the periodic table.