When to leave a child home alone is dependent on the maturity of each individual child and the level of preparedness.
Children older than 12 years old can babysit younger siblings, but not overnight and not for a period more than 4 hrs.
If a 9-11 year old is deemed mature and ready, he/she could be left alone for up to 2 hours. However, they should not be left in charge of younger siblings.
Parents are ultimately responsible for their children’s safety.