discrepancy in the solution of various instituites

ya but this is wat fiitjee says." All four planar bonds (F−Br−F) will reduce from 90° to 84.8° after lp − bp repulsion."

but even thgh i thnk the arrangement wuld have been as lp on the axis with one F and 4 F on the plane, to avoid repulsion so why again we need to consider replulsion for bond angle.
Moreover in the xam i confidently rote the answer as 4 as i thgt i am correct but since then i got to learn solutions of many institutes and every one says it shuld be zero.

I just dont get it how ...[7]

Moreover i have another doubt
why shuld the fission reaction be like this :
₉₂U²³⁵ + ₀n¹ → ₅₄Xe + ₃₈Sr⁹⁰ + 4₀n¹.
since we know that fission reaction occurs by bombardment of neutrons to the nucleus then how everyone's mentioning reaction as ₉₂U²³⁵ → ₅₄Xe + ₃₈Sr⁹⁰ + 3₀n¹. [7]

i thnk my understanding is reasonable enough.
but IIT this time sucked.[59]

the ans shud be 4

Yup...it sucked big time!!!!!!!!!!!

now..for that I have no doubt..i agree with others..its HIGH time that they put a RE-TEST..

When, i initially saw the prob even i thought the as would be 4.
but the ans is 0 itself.
Take 4 pens in ur hand then tilt all pens below by the same angle 45° just think that would it remain 90°.
no all the 8 angles will change. i dont know by how much exactly but they will surely do change.
try evrything practically u will surely get the ans

for small angles it mey appear that the angle remains 90° but it actually changes although by a small amount