Question

An equilateral quadrilateral is a square

Answer 1

Righto

Answer 2

Yes it is :)

Answer 3

Not a square in general. It is a rhombus.
http://en.wikipedia.org/wiki/Rhombus

Answer 4

Yes, @eliassaab, a rhombus is a square.

Answer 5

A square must have every angle = 90. A rhombus does not have too in general..

A square is rhombus but a rhombus is not in general a square