Question

which feature helps a coconut fruit to float in water​

Answer 1

It is hollow from inside i.e it has air pockets and it's density is more than so it floats on water. If something has more density than water then it will floats so coconut floats.

Answer 2

Coconut fruit has a huge hollow inside it which is mostly filled with air .Air having a lower density and lighter than water it helps the coconut to float.