Yes they probably can yes
Legally, laws about this, if there are any, would vary from state to state. Ultimately, this would be decided by the 15-year-old's parents, and it is not so much a question of "can" as it is "should" and "Is it wise" to allow a 15-year-old to stay home alone for two weeks. The answer to that is an emphatic "NO!" While it is fine to allow them to stay home alone for short periods of time, two weeks is simply too long to leave them alone to take care of themselves day in and day out.
no they can't
yes if s/he is trustworthy
1 year and 34 days
Absolutely NOT!!! No matter how responsible, 16 years old is not an appropriate age to stay home alone for that amount of time.
Yes. An 18-year-old is an adult.
No way!
it is 14 year old
=yes.=
There is no law addressing this.
Yes, they are 16 give them some space.
No, you have to be around 15/16+ to stay at home with a younger sibling/relative.