Answers

a. Why do so many men go bald but almost no women?

Because of a chemical in their bodies called testosterone. Women  don't because testosterone  is only present in smaller quantities in their bodies

b. Why do we laugh when people tickle us?

Because we experience a feeling  similar to when spiders or small insects crawl all over us.  This same feeling sends us into a state of panic and elicits a response of uncontrollable laughter.

c.Why do some people sleepwalk?

No one is quite sure but it is thought that it happens  when there is sudden  activity in the brain during very deep sleep

d. Why do people yawn- and why do people cover their mouth when they do it?

It is the result of the body's need for extra oxygen. Reason to cover one's mouth : good manners  or originally  from fear that the soul might leave the body when the mouth  was open.

e.What causes hiccups and what’s the best way to stop them?

They are caused by a spam , a sudden muscle movement in the diaphragm. The best way to stop them is to concentrate  on something else.

f.Why do people say “bless you” when someone sneezes?

The custom stems from the Middle Ages , when the Bubonic plague was common and the final stages of this disease was prolonged sneezing