Does the lock(objlocker) make that object thread safe app wide? And are static members automatically thread safe?

static void AddItems(  )
  {
    for (int i = 0; i < 100; i++)
      lock (list)
        list.Add ("Item " + list.Count);

    string[] items;
    lock (list) items = list.ToArray(  );
    foreach (string s in items) Console.WriteLine (s);
  }

lock (list)
        list.Add ("Item " + list.Count);

lock (list) items = list.ToArray(  );

class UsefulStuff {
    object _TheLock = new object { };
    public void UsefulThingNumberOne() {
        lock(_TheLock) {
            //CodeBlockA
        }
    }
    public void UsefulThingNumberTwo() {
        lock(_TheLock) {
            //CodeBlockB
        }
    }
}

public class Foo
{
    private static Foo instance = new Foo();

    public static Foo Instance
    {
        get { return instance; }
    }
}