How much weight can I hang from a drywall ceiling?
Ideally this should be screwed/anchored into a joist for maximum support. However, if you really want to use a drywall anchor, you should use a toggle bolt or a ceiling anchor.  Instead of just screwing into the wall, these expand to several times their size which gives you a good hold, especially when the force is pulling directly down.  10lbs might be pushing it though, it will depend on the thickness of your drywall and the overall condition.  The worst case is you just have to patch the hole and repaint; drywall is pretty forgiving like that!