Which of the events listed below is not observed during mitosis?

1. Chromatin condensation
2. Movement of centrioles to opposite poles
3. Appearance of chromosomes with two chromosomes joined together at the centromere
4. Crossing over

Class 11 pg 167
(d) Crossing Over is the phenomenon of genetic exchange between homologous  pair of chromosomes and is a characteristic feaiure of meotic cell division. It does not occur in mitosis.
Rest of the options represent stages in mitosis.