What would happen if one of the replicated chromosomes one of the two intermediate daughter cells failed to split at the end of metaphase ii? what were the four new daughter cells look like?

Two normal haploid daughter cells (n), one daughter cell with one extra chromosome (n+1) and one daughter cell with one less chromosome from the haploid set (n-1).

Explanation:

Failure of sister chromosomes to separate from each other at the end of metaphase II is called as nondisjunction at meiosis II. It leads to formation of four daughter cells with different number of chromosomes. Out of total four cells, two daughter cells have a complete haploid set of chromosomes and are normal. The third daughter cell has one extra chromosome and is denoted as "n+1". On the other hand, the fourth daughter cell lacks one chromosome from the haploid set and is denoted as "n-1".

they float because they are less dense than the water itself

something denser than water, like a rock, will sink to the bottom