DEAR VIPIN SIR NE JO STRUCTURE BANAYA HAI SEE THAT
THERE IS 2 sp2 hybridized boron and 2 sp3 hybridized boron is present
if the question is asked how many B-O-B BONDS ARE PRESENT IN BORAX STRUCTURE
THE THE CORRECT ANSWER IS 5....
IF WE ASK HOW MANY B-O-B BONDS AROUND sp3 boron then right answer is 3.
F WE ASK HOW MANY B-O-B BONDS AROUND sp2 boron then right answer is 2.
hope you got my point....