If vectors are arranged as trigonal planar and have equal magnitude, it is an ideal case of zero resultant.
In mitosis, the prophase is further understood by dividing it into the given sub-stages:
1.Leptotene :
In this stage the nucleus enlarges in size in the chromosome. The chromosomes appear thin, thread-like and single-stranded in this stage. They have swollen or beaded structures along their length and their ends appear converged towards one side of the nucleus called bouquet.
2.Zygotene:
In this stage, the identical chromosomes come together and form bivalent or homologous pairs. Further, ...
In benzene molecule, carbon and carbon bond can't have polarity because there is not any electronegativity difference and the carbon hydrogen is also not much polar because the electronegativity difference is almost zero and also the small pull due to small difference in Electronegativity is balanced due to even pull from all directions.
In chlorobenzene the electronegativity difference between carbon and chlorine is very high so, it is polar.
(to compare polarity first check electronegativity...