Is zakat obligatory on investment certificates designated for orphans, and how is it calculated? Is it permissible for their uncle to pay it on their behalf from his own money, especially given their need for the amount to start their professional lives?

The guardian of an orphan's wealth must pay zakat on behalf of each orphan if their wealth reaches the nisab. As for the children themselves, they must pay zakat on their own wealth after reaching maturity, because the bank usually does not pay zakat, and if it does, it is not sufficient unless it is with their permission. They must estimate the wealth annually and seek assistance from the bank to ascertain its value. Zakat is not waived for them due to their need for money. Their paternal uncle or someone else can pay zakat on their behalf after they reach maturity, with their permission. However, before maturity, permission is not required if their guardian is managing their affairs. If someone else is managing their affairs, then their permission is necessary.