How is the zakat on money calculated, and is the nisab determined by gold or silver, and what is the accepted purity standard, and to whom is the zakat given, and what about money that may have reached the nisab at an unknown earlier time?

The nisab (threshold) for Zakat on money is determined based on the nisab of gold or silver. The standard purity for gold is 24 carats, and for silver, it is pure silver. Zakat is paid to the eight categories of recipients mentioned in the Quran. The Zakat year (hawl) begins when the money reaches the nisab, not from the time a fatwa (religious ruling) is received. If the exact time the nisab was reached is unknown, an estimation should be made by referring to bank account statements.