Answers

2016-03-17T15:40:59+05:30
Becausec electron affinty increase from left to right and decreases down a group
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2016-03-17T17:43:13+05:30
Basically the electron affinity depends on atomic radius and nuclear charge. 
when we go down a group , the atomic radius increases so the electron affinity decreases 
the nuclear charge increases so the electron affinity should increase but the electron affinity decreasing dominates over the rise due to nuclear charge
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