$A$ family has five girls and no son. What is the probability of having a son as the $6^{th}$ child (in $\%$)?

The chromosomal theory of sex determination was propounded by:

Match the following columns:

Column-$I$	Column-$II$
$(P)$ $(X+O)$	$(i)$ Genetic constitution in Drosophila
$(Q)$ $(XX+XY)$	$(ii)$ Genetic constitution in grasshopper
$(R)$ $(ZZ+ZW)$	$(iii)$ Sex determination in birds
$(S)$ $(AA+XX)$	$(iv)$ Sex determination in humans

Sex determination in humans is identified by:

$A$ man affected by a certain disease marries a normal woman. They have $8$ children ($3$ daughters and $5$ sons). All the daughters suffer from their father's disease,but none of the sons are affected. What type of inheritance can you suggest for this disease?

The chromosomes which determine the somatic characters are called