If a compulsory ghusl was not taken before ending of Sehri,, will the fast be valid?

Answer

Ghusl should be made as soon as possible. However, even if it was not made immediately, and was delayed until after ending of sehri time, the fast will be valid. Whilst ghusl should be taken as soon as possible, it will not invalidate the fast if ghusl had not yet been made.