No, two fourth is not an improper fraction because the numerator is less than the denominator if it was improper it would be four over two which you can change it into a mixed number.
5/4
13/4
19/4
21/4
9/4
5/4
eleven over four
Two and four sevenths as an improper fraction = 12857/5000
That would be 41/4
325/100 or 13/4
625/100 or 25/4
You can't. Improper and proper fractions are two different things. You can convert an improper fraction to a mixed number.