Evaluating each genetic condition. Klinefelter's syndrome is correctly described as 47, XXY, involving an extra X chromosome in males.
Turner's syndrome should be 45, X, not 45, XY. This syndrome is characterized by the presence of a single X chromosome and the absence of the second sex chromosome, not an XY configuration.
Down syndrome is accurately described as having an extra 21st chromosome, leading to a total of 47 chromosomes.
Edward syndrome is also correctly identified with an extra 18th chromosome, resulting in 47 chromosomes.
If the potential difference across \(PQ\) is 4V, the potential difference across \(A\) and \(B\) in the given figure is: