What are sex chromosomes? Which sex chromosomes are found in male and female human beings? State the chromosome responsible for the development of a male child in human beings?

(N/A) Sex chromosomes are a specific pair of chromosomes that determine the biological sex of an individual.
In human beings,females possess a pair of $XX$ chromosomes,while males possess one $X$ and one $Y$ chromosome $(XY)$.
The $Y$ chromosome is responsible for the development of a male child. When a sperm carrying a $Y$ chromosome fertilizes an egg (which always carries an $X$ chromosome),the resulting zygote has $XY$ chromosomes,leading to the development of a male child.