Question

Why is second position of furan preferred for electrophilic substitution?

Answer 1

it
puts negative charge at the 3 and 4 positions (see the . But the proximity of the positively charged, electronegative nitrogen atom to the 2 and 4 positions makes those resonance structures stronger contributors to the total electron density in the ring, so the 2 and 5 positions are a bit more negative than 3 and 4.

You can get substitution at the 3 and 4 positions, but not as easily.