In human males and females, how many pairs of chromosomes are identical (in $pairs$)?

All human races,such as Africans,Asians,Europeans,Americans,and others,might have evolved from a common ancestor. Provide a few pieces of evidence in support of this view.

In human males,all the chromosomes are paired perfectly except one. These unpaired chromosomes are:
$(i)$ Large chromosome
$(ii)$ Small chromosome
$(iii)$ $Y$-chromosome
$(iv)$ $X$-chromosome

By the process of artificial selection in evolution, which of the following is developed using sterile flowers?

With the help of suitable examples,explain why certain traits cannot be passed on to the next generation. What are such traits called?

In human beings,the statistical probability of getting either a male or female child is $50 : 50$. Give a suitable explanation.