Answer: Because the acre is a measure of area, it has no definite perimeter. For example, using the examples in question one, the perimeter of the long, skinny sidewalk acre would be 17,434 feet (more than 3 miles), but the perimeter of the square acre would be 835 feet.
No other molecular fluoride of krypton has been isolated, so all krypton compounds are derived from KrF 2, where Kr is in the +2 oxidation state. Krypton difluoride is a powerful oxidative fluorinating agent. (Its oxidizing power means that it extracts electrons from other substances and confers on them a positive charge.
Origin of kryptonite After Kryptonite a fictional radioactive mineral (the presence of which weakens the superhero Superman) appearing in Superman comics from 1949 onwards Krypton the home planet of Superman where Kryptonite was once found before being scattered in the universe by the planet's destruction (named by American comics writer Jerry Siegel (1914-1996), perhaps after the element krypton) -ite 1