Haemophilia $A$ is due to the absence of

In a normal couple,half of the sons are hemophilic and half of the daughters are carriers. Where is the gene located?

Sickle cell anaemia is due to

Choose the correct option for the offspring of a colorblind woman and a normal man.

Blackening of urine,when exposed to air,is a metabolic disorder in human beings. This is due to:

$A$ man whose father was colorblind marries a woman who has a colorblind mother and a normal father. What is the percentage probability of their male children being colorblind (in $\%$)?