What is the common frequency of ac in homes in the United States? How many 7 digit phone numbers can be formed in an area code, if the symbols 0 and 1 can not be used as the first digit of the phone number? The solubility product for chromium(III) fluoride is Ksp = 6.60 X 10-11. What is the molar solubility of chromium(III) fluoride?